I was going one-by-one through the new content in OS V3.0 and noticed something strange and was able to reproduce it several times. I do not have a "sure fire" way of invoking the strangeness - but it wasn't difficult to try several times and 1-in-5 or so tries would go strange on me.
I was going between "First Strike" and "The Polysynth MW" - they're neighbors in the Category Search ordered by default while showing all presets. The first time I noticed this I was done "playing" with "First Strike" and switched to the next Perf ("The Polysynth MW" ) and boom - first time the strangeness happened. The drums from First Strike continued to play after the switch. When I lifted my hand from the keyboard - the "First Strike" drums were still playing. Not the entire ARP - but just a short part of it in a loop (1 measure? maybe 2 beats?).
What I'm accustomed to is that when switching performances - if I'm switching FROM a Performance with an ARP and/or motion sequence - the ARP and motion sequence of the "from" Performance will stop as soon as I switch Performances - even if held notes continue to sound from SSS. I am not accustomed to this kind of thing like an ARP to continue. Seems like some residue. Maybe something new in the pattern player that "shares" this memory not clearing when I switch and the residue playing. Who knows.
I went back to "First Strike" and tried reproducing. It didn't happen every time. Sometimes I'd switch the [SCENE] button (pick a different scene number) before the switch. I'm not sure which scene I was on the 1st time I did the switch. I varied how long I would hold down notes before switching. At any rate - every once and a while I could make "this" happen.
It's better heard than described. Maybe try to reproduce on other keyboards.