Empty Staves show when Multi-Measure Rest (M) is active (MuseScore 4.0.1)

I've attached a snippet for explanation. I have noticed that if the primary staff has multi-measure rests, the other staves are shown when M is pressed (or selected on the Style page) to display the multi-measure rest. Any ideas on how to stop this from happening?

I've tried copying and pasting in to a new file just to be sure there was nothing amiss in my original. I've tried to dissect the XML.