Crash after copy-paste linked measures before a system change with multimeasure rests
1) "My First Score"
2) Enter a whole note in the first measure -> Exit note input mode
3) Press "M", for enable multimeasure rests.
4) "I" -> Add a linked staff -> Ok
5) Select the first measure of the linked staff (bass clef)
6) Copy-paste three times this measure, or, faster: press "R" key three times
So far, so good. But you've noticed the first break line has appeared. You are at the critical point.
The picture below has been produced with a minimal test file, with an added break line. This one (similar steps, but only copy-paste twice, at step #6): four measures break line.mscz
6) Press again "R" key, or copy-paste again.