Empty Staves show when Multi-Measure Rest (M) is active (MuseScore 4.0.1)
S4 - Minor
When the Hide Multi-Measure Rest option is selected, either with M or through the Style page, an empty staff will show even though there's nothing in the other staff. I tested it in 3.5.6 and the staff hides as expected.
See https://github.com/musescore/MuseScore/pull/15418; this will be fixed in MuseScore 4.0.2 when that comes out.
Automatically closed -- issue fixed for 2 weeks with no activity.