Hi,
Thanks for the reply.
I have the MAC version of BIAB 2018 + upgrades 2019 and 2020. In this case it was the electric guitar 1924 in style _TRINITY, but it also occurred in other styles and instruments. String quartets are also very sensitive in this matter.

I have no frozen tracks. I have tried everything. Simplifying and disabling the natural arrangement didn't work. I have tried to change it in the chord builder, but it didn't react.Finally I found out that adding another bass note (slash root), e.g. changing a G into G/B on the first note, solved the problem. This gives a dissonant to the other instruments, but if you import it as a separate track to your daw, it is a solution. If you know another way then I am very interested.