I experience the exact same problem.
I use Helix in Snapshot mode and via the Instants I switch my H&K Switchblade and a Whammy DT. Both with Program Change messages.
Therefore I need 3 Instants:
Instant 1: MIDI CH 1 - Amp switching
Instant 2: MIDI CH 3 - Whammy Section switching
Instant 3: MIDI CH 3 - DropTune Section switching
So far, so good. I got my Helix in March, updated it to 2.53, looked for an amp and cab that sounds close to mine in the rehearsal room and set up my presets.
Sounds: check. Then I copied my Presets, exchanged the ampsim for a loop, got rid of the cabsim, programmed the Instants and were good to go.
First rehearsal: Everything's up and running, no issues - I love when a plan comes together.
Second rehearsal: Suddenly the amp stutters, when it's switched
Troubleshooting:
Change MIDI Cable - still stutters
Connect MIDI Cable directly with Helix - still stutters
Changing from Clean (Ampsim) to OD (H&K) [in the same Preset] - stutter
Changing from OD (H&K) to Clean (Ampsim) [in the same Preset] - no stutter
Changing from Cln/Crnch (H&K) to OD (H&K) [in the same Preset] - stutter
Changing from Cln/Crnch (H&K) to OD (H&K) [in another Preset] - no stutter
Visiting my Testcenter (Preset with no Instants, The Footswitches send Program Change messages to switch my Amp)
Everything works fine. No stutter at all.
"Have you tried to turn it on and off again?" - "Umm, no. Okay, let's restart the thing."
Everything worked as it should...
Third rehearsal: The amp stutters, when it's switched. Multiple restarts don't help "Guess I'll have to live with it today"
At home:
Installed MIDI OX to monitor what "lil' Helix - the PCM Gangsta" tells my gear via MIDI.
"Aha. So you're sending your messages up to three times. You really want to be heard, don't you?"
Deleted all Instants.
Setting up the first:
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0 (Snapshots 1-8) -> 1 PCM send when switching, looks good. save.
Setting up the second:
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21 -> 2 PCM send when switching. That's bad. It should be 2-1-2-2-2-2-2-2, checking first Instant.
CH1, Program: 0 - 0 - 0 - 0 - 0 - 0 - 0 - 0 -> okay, let's re-edit.
-> Changing Snapshot 2 from 0 to off -> now let's check the other values
CH1, Program: off - off - off - off - off - off - off - off
Checking the sent Messages: everything doubled. okay. let's re-edit Instant 1 anyway.
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Checking the sent Messages:
Pressing Snap 1: 4 messages (CH1|0, CH3|21, CH1|0, CH3|21)
Pressing Snap 2: 3 messages (CH1|0, CH3|21, CH3|21) - ??? - let's hit it again
Pressing Snap 2: 2 messages (CH3|21, CH3|21) - seems more legit
Pressing Snap 3: 3 messages (CH3|21, CH1|0, CH3|21) - okay, hit it again
Pressing Snap 3: 4 messages (CH1|0, CH3|21, CH1|0, CH3|21) - at least some consistency
Pressing Snap 4: 4 messages (CH1|0, CH3|21, CH1|0, CH3|21) - as I expected
Pressing Snap 5: 4 messages (CH1|0, CH3|21, CH1|1, CH3|21) - not as I expected
Pressing Snap 6: 4 messages (CH1|1, CH3|21, CH1|1, CH3|21) - as I expected
Pressing Snap 7: 4 messages (CH1|1, CH3|21, CH1|0, CH3|21) - eventually, I now was expecting this
Pressing Snap 8: 4 messages (CH1|0, CH3|21, CH1|0, CH3|21)
Okay. Pressing Snap 1, Hit save 2 times, change preset and go right back again
Pressing Pres up: 2 messages (CH1|0, CH3|21) + 4 messages (Helix Preset changing)
Let's set up the third:
Turning the Command knob of Instant 3 resets Instant 1 to
CH1, Program: 0 - 0 - 0 - 0 - 0 - 0 - 0 - 0, Instant 2 doesn't seem to be effected
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Okay, re-edit -> Changing Snapshot 2 from 0 to off -> now let's check the other values
CH1, Program: off - off - off - off - off - off - off - off, continuing re-edit
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 67
Checking the sent Messages:
Pressing Snap 1: 6 messages (CH1|0, CH3|21, CH3|67, CH1|0, CH3|21, CH3|67)
Pressing Snap 2: 4 messages (CH3|21, CH3|67, CH3|21, CH3|67) - Hey, the unexpected CH1 message disappeared
Pressing Snap 3: 6 messages (CH1|0, CH3|21, CH3|67, CH1|0, CH3|21, CH3|67)
Pressing Snap 4: 6 messages (CH1|0, CH3|21, CH3|67, CH1|0, CH3|21, CH3|67)
Pressing Snap 5: 6 messages (CH1|1, CH3|21, CH3|67, CH1|1, CH3|21, CH3|67)
Pressing Snap 6: 6 messages (CH1|1, CH3|21, CH3|67, CH1|1, CH3|21, CH3|67)
Pressing Snap 7: 6 messages (CH1|0, CH3|21, CH3|67, CH1|0, CH3|21, CH3|67)
Pressing Snap 8: 6 messages (CH1|0, CH3|21, CH3|67, CH1|0, CH3|21, CH3|67)
Okay. Pressing Snap 1, Hit save 2 times, change preset and go right back again
Pressing Pres up: 3 messages (CH1|0, CH3|21, CH3|67) + 4 messages (Helix Preset changing)
Now let's delete Instant 3
Checking the sent Messages:
Pressing Snap 1: 2 messages (CH1|0, CH3|21)
Pressing Snap 2: 1 messages (CH3|21)
Pressing Snap 3: 2 messages (CH1|0, CH3|21)
Pressing Snap 4: 2 messages (CH1|0, CH3|21)
Pressing Snap 5: 2 messages (CH1|1, CH3|21)
Pressing Snap 6: 2 messages (CH1|1, CH3|21)
Pressing Snap 7: 2 messages (CH1|0, CH3|21)
Pressing Snap 8: 2 messages (CH1|0, CH3|21)
Okay, might be a workaround.
Reloading the Preset and adding a fourth Instant command
Turning the Command knob of Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 67 - hey, nice...
deleting Instant 4
Checking the sent Messages:
Pressing Snap 1: 3 messages (CH1|0, CH3|21, CH3|67)
Pressing Snap 2: 2 messages (CH3|21, CH3|67)
Pressing Snap 3: 3 messages (CH1|0, CH3|21, CH3|67)
Pressing Snap 4: 3 messages (CH1|0, CH3|21, CH3|67)
Pressing Snap 5: 3 messages (CH1|1, CH3|21, CH3|67)
Pressing Snap 6: 3 messages (CH1|1, CH3|21, CH3|67)
Pressing Snap 7: 3 messages (CH1|0, CH3|21, CH3|67)
Pressing Snap 8: 3 messages (CH1|0, CH3|21, CH3|67)
Okay, let's make it interesting
Change Instant 3 on Snap 8 to 46
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 66 - 66 - 66 - 66 - 66 - 66 - 66 - 46 - ???
re-editing Instant 3 Snap 1 - Snap 7 to 67
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 46
Turning the Command knob of Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 67 - whispering the beginning of Slipknot's 'Duality'
Re-edit Instant 3 on Snap 8 to 46
CH3, Program 66 - 66 - 66 - 66 - 66 - 66 - 66 - 46
re-editing Instant 3 Snap 1 - Snap 7 to 67
deleting Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
CH3, Program 46 - 46 - 46 - 46 - 46 - 46 - 46 - 46 - I'm getting to Limp Bizkit's 'Break Stuff', the chainsaw part...
Obviously, it doesn't want me to make changes on the last Instant, so let's swap Instant 2 and 3
CH1, Program: 0 - 0 - 0 - 0 - 0 - 0 - 0 - 0
CH3, Program 46 - 46 - 46 - 46 - 46 - 46 - 46 - 46
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21 - lollipop you Helix. Really, lollipop you, you lollipopin' lollipop
re-editing
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 46
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Turning the Command knob of Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 46 - 46 - 46 - 46 - 46 - 46 - 46 - 46
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21 - okay...
re-editing
deleting Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 67
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Okay. Turning the Command knob of Instant 4. re-editing
changing all the 21s to 22s and back again
deleting Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 46
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21 - nice...
Checking the sent Messages:
Pressing Snap 1: 6 messages (CH1|0, CH3|67, CH3|21, CH1|0, CH3|67, CH3|21)
Pressing Snap 2: 4 messages (CH3|67, CH3|21, CH3|67, CH3|21)
Pressing Snap 3: 6 messages (CH1|0, CH3|67, CH3|21, CH1|0, CH3|67, CH3|21)
Pressing Snap 4: 6 messages (CH1|0, CH3|67, CH3|21, CH1|0, CH3|67, CH3|21)
Pressing Snap 5: 6 messages (CH1|1, CH3|67, CH3|21, CH1|1, CH3|67, CH3|21)
Pressing Snap 6: 6 messages (CH1|1, CH3|67, CH3|21, CH1|1, CH3|67, CH3|21)
Pressing Snap 7: 6 messages (CH1|0, CH3|67, CH3|21, CH1|0, CH3|67, CH3|21)
Pressing Snap 8: 6 messages (CH1|0, CH3|67, CH3|21, CH1|0, CH3|46, CH3|21)
Okay. Pressing Snap 1, Hit save 2 times, change preset and go right back again
Pressing Pres up: 3 messages (CH1|0, CH3|67, CH3|21) + 4 messages (Helix Preset changing)
Turning the Command knob of Instant 4, re-editing, turning the Command knob of Instant 5, re-editing
Deleting Instant 5
Checking the sent Messages: as above
Deleting Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 46 - 46 - 46 - 46 - 46 - 46 - 46 - 46
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Turning the Command knob of Instant 4, re-editing, turning the Command knob of Instant 5, re-editing
Deleting Instant 5
Checking the sent Messages: as above
changing every value by 1 and back again - checking on send messages, everything gets send 3 times (could I get 4x?)
Deleting Instant 4
CH1, Program: 0 - off - 0 - 0 - 1 - 1 - 0 - 0
CH3, Program 67 - 67 - 67 - 67 - 67 - 67 - 67 - 67
CH3, Program: 21 - 21 - 21 - 21 -21 -21 - 21 - 21
Yeah, that's it, tried to get Swanny's CC setup to work properly, It seems you can't get it working with two or more values that change, no matter if you use PC or CC or mixed things.