ha, that´s certainly an interesting one!
could you try splitting up your setup a bit to zone in on the error?
It´s always easier to find an error with fewer components involved.
let´s say try to use the zaquencer as master hooked up to just the synth and the drums.
also in the video I noted that your 3 midi lights in, outA, outB were continuously lit.
thist doesn´t mean anything bad per se, but could hint to some midi loop thing.
also, what´s the setting of “transpose enbl” (encoder 8) in global menu?
make sure to try it with “off”.
please keep us posted here!