Here are my steps leading to the problem (screenshots below).

I have since found that in addition to a time-signature in every bar/measure, the bar numbers disappear when adding part-makers, copying parts or adding section-letters. I'm not sure of the precise combination at which the bar-numbers disappear.

I rely on those bar numbers heavily for larger scores so this is a particular problem for me.

Changing Time-Signature


Selecting New Time signature


New time-signature Score


No Bar/Measure Numbers