I thank you for your suggestion, but in my case: definitly not. Tempo was synchronized. Now I have tried a second song, that I had once made on the standalone BIAB 2020 version in the FL Studio VST and I also installed Reaper, and used the BIAB VST there: same behavior. After bar 32 there is an end end drum fill, but all other instruments are going on as normal. I am using a lot of manual grove changes in the chord sheet and also style mix or changes of the drum sets. I am still guessing, that this is, what the VST version can not handle.