Deleting local key/time signature where a global key/time signature change takes place is very inconsistent

Repoducibility should be "often", but there isn't such choice.

The thing that actually happens cannot be described in a few words because it varies from place to place, and making a complete summary is difficult. And not as important as looking into the code and finding the issues.

Sometimes the global key signature disappears along with the local key signature, sometimes the global key signature remains but all other local key signatures are gone, sometimes all things are normal.

Checked for local time signature, and the global time signature always seems to disappear.