In the M9 you could get the unit to start at the top of a pattern tremolo phrase by hitting the tap button once. It also restarted the tremolos back on the downbeat. I can't seem to get the HX Effects to do that! It makes the Bleat Chop Trem just a random out-of-sync effect.
Hopefully if this isn't possible now, it would be added in! Also, if the HX would respond to Midi Stop/Start commands that would be great. That way fx could be triggered in time.
Here's what was in the old M9 Advanced manual:
Re-syncable LFO
Sync your Mod FX to the downbeat by simply hitting the TAP switch while playing.