It seems that the problem is on the HD500 foot switch MIDI assignments. Try assigning MIDI note C2 to HD500 foot switch FS1 in one of the presets. Using POD HD500 Edit and your HD500 connected to the computer using USB:
- Run POD HD500 Edit
- Select one of the presets
- On the 'CONTROLLERS' tab (this is where you see FX, AMPS, MIXER, CONTROLLERS, SET LIST menu boxes below the signal chain), go to MIDI ASSIGN. Under FOOTSWITCH/EXP, select FS1 by turning the knob next to it on the left side. Under MESSAGE, select Note On (using the knob on the left). Under NOTE, select C2. Under MIDI CHANNEL, set it to Base. Under VELOCITY, set it to 100
- Now, you need to send this modifed preset to HD500 by clicking the 'Selected' button under SEND on the upper left hand side of HD500 Edit. Make sure that the modified preset is seleted before clicking the "Selected Button"
Now in Live, map FS1 foot switch to clip 1 on track 1. Once you mapped it, on the MIDI mappings, you should see, "1, Note C1, 1-MIDI, Slot 1". On Clip 1 Track 1 slot, you should see 1/C1. Note that the MIDI Note is one octave lower in Live (HD is C2 and in Live, it's C1) and it's fine. Test and hopefully, it works. If it doesn't, let me know. I'll be happy to send you my HD500 preset as well as a test Live project that has the MIDI mapping.