Anecdotally, I've realized that this only occurs for me if I have an expression pedal plugged into EXP1/2 and I'm trying to use FS7 or FS8 via MIDI. As soon as I unplug the expression pedal, FS7 and FS8 work. My workaround was to use an Ampero Control external midi controller which has expression inputs, so that everything is MIDI including the expression pedal. Now I have zero issues. YMMV