"Repeat measure sign" affects all staves
steps to reproduce:
1) have at least two voices in the score
2) enter a melody that is two measures long and has different notes in each measure in the first voice
3) put something else the first measure of the second voice
4) put a repeat measure sign in the second measure of the second voice
--> the first measure is played twice, the part of the melody second measure is replaced by the part in the first measure
alternatively open file in the attachment and play.