That link I provided should detail what parameter the FREEZE option is on for each algorithm. I think most of them on the DECAY parameter, except for BLACKHOLE and SHIMMER where FREEZE is on the FEEDBACK parameter on the Space FXMIX knob.
I you assign the HotSwitch to FREEZE (and not INF) on the BlackHole Feedback parameter and it acts like infinite (but still reads FREEZE on the knob in H9 Control) then that's probably a bug. FREEZE should not allow any build up. Make sure nothing is reading INF (either in H9 Control or on the pedal itself) when you do the HotSwtich. If anything is reading INF, let me know and I'll take a look at it, that could also be a bug.
