Hello, my first post too.
I have the same problem with my brand new H8000FW 5.5b.
Calibrating and setting up the pedals works perfectly, but only for a while. After some time the pedals freak out and start jumping around, sometimes one of them becomes completely unresponsive. They also interact with each other, I can see that in the pedal setup page. Clearing assignments, calibrating pedals or rebooting does not help. Loading an old setup from card does not help either, only clearing setup in the service menu gets the pedal setup working. Until it happens again.
I have a feeling it only happens here when assigning a pedal to wet/dry, but cannot confirm this yet, as it sometimes takes a long time until the misbehavior happens, and I mostly want to control wet/dry with the pedals anyway
Could this be a bug in 5.5b? There is also some strange "stickiness" in the assignments. If I clear/reset an (wet/dry) assignment, sometimes the blinking underline just doesn't go away, and the pedal still controls that parameter. It seems to work more reliably if I first set the assignment to "high", leave the page, and return to set it to off. Sometimes this has to be done several times until the assignment is really cleared.
I doubt these are hardware issues because after clearing the setup and re-assigning the pedals they work perfectly right away.