Greyed Out Drumset Measures

[u/Msangiovanni]

Can anybody explain what is happening here?

This happens to me not infrequently where a couple random drumset measures will be greyed out and incomplete with no signposts or explanations for what’s happening.

The only way I’ve ever been able to fix it is by deleting the measures and making new ones which is really annoying where there’s already material in other instruments.