Changing Time Signature causes existing measure rest to move
I have experienced on several occasions where changing the time signature moves the measure rest to another spot in my score. The rest will jump to somewhere else in the score. Often it jumps to the end just beyond the staff (in continuous view), but testing this score it jumped to another random measure or simply disapears in every staff in that measure.
I work around this by inserting a key signature into the measure where I'm changing the time signature, insert new time signature, click on measure to select entire measure, "Delete" to delete the measure with the meaningless key signature. It also works if I add staff text rather than a key signature. Sometimes, but not always, I can delete the offending measure without adding anything to it. When that measure is deleted the time signature is still there and the rests are all lined back up where they belong. Here is a link to the score it last happened on:
On this score append a few measures to the end and change one of the new measures time signature and you will see what I mean.