Looking at our release notes for FMOD Studio version 2.03.04, I see this bullet point:
- Fixed adjusting the length of a transition timeline could sometimes cause parts of the track to be draw in black.
It sounds like this bug was fixed in the version of 2.03 branch that was released after the version you’re using. If you upgrade to FMOD Studio version 2.03.04 or later, does the bug persist?