I must admit I am scratching my head with this one. You are right it does seem like a midi loop of some kind. I set one up deliberately to compare it.
However when I created this condition the effect was immediate. where as when I am hooked up how I need it I can be running for hours then Booof! It will crash when playing, but in any state i.e. grid, page/ no rec/ rec what ever no decernable pattern. Here is the logic of my midi:
Octopus->out to Xstation->in
xstation->in to USB (computer live with drum samples and softsynths)
xstation->out to moog->in
moog->out to octopus->in
so the only path back to the octopus in the moog and this is a midiout not midithru
I use the moog as the input for recording to the octopus which works fine
I send drum midi from the octopus to live through the xstation via its internal midi to usb and the moog from the octopus to the xstation midi out to the moog.
One option I suppose is to isolate the moog on the second octopus midi output midi, but I’d prefer otherwise if possible.