Musescore 2 to 3 oddity

Hi
I created a score in 2 point something and have opened it in 3. Most everything is hunky dory. However (as you'll see in the screenshots) where there was a 4 bars rest before a repeat, MS3 has made it 3 bars(with repeat sign) followed by 1 bar (with repeat sign). Well that's ok, I can delete the spurious repeat bar using an ordinary bar line. BUT how do I the get the 3 + 1 bars to join into 4 bars of rest?
I have a horrible feeling I should know how to do this....
Oh by the way, it's all fine in the full score. No erroneous things happening there.