Yes I think it’s a bug. I just ran a few tests and you are right - it only seems to be a problem with external hardware, virtual MIDI works fine. Tested using preroll on FunkBox, DrumJam, MoDrum and Boom 909. All started just fine. Tested with TR-8, TB-3, TT-303 and Volca Bass and none of them started at end of preroll. I’ve also found that there’s not a problem if you only use 1-bar of preroll, so it only occurs when using 2, 3 or 4 bars. I can see from my external machines start/stop lights that a brief message is received at the beginning of the preroll, but anything more than 1-bar of preroll and they won’t start. Steinberg, can you confirm?