odd tempo bug when using control z to return to previously set tempo

used control z to take a song from 120 bpm back to 100 where it was originally but the bass part was staying at the faster tempo and the other parts were dragging along in a very odd way that i can't really describe I fixed it by just putting it back to 120 in the actual sheet music then typing in 100 as shown in this video thought i should share it here incase it hasn't been looked at or heard of yet
https://youtu.be/3oxryOgxBag