Key Signatures are inaccurate in parts compared to the score
The key signatures in one of the separate parts in my score does not have the same key signature as the rest of the score, even though it is all in concert key. Not sure if this has anything to do with it, but it is the one part in the score that has a mix of drumsets and melodic instruments, besides the main score.
To reproduce, try creating a separate part with a mix of drumsets and melodic instruments, specifically keyboards in this case.
The screenshots and file show what I mean.
OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (64-bit): 126.96.36.19937, revision: b5add95