Well this is new… not sure what to make of this one pay attention to the Bass staff’s chord symbol in bar 15. (sorry the video turned out quite small after upload)
This is only happening in Galley View, so it’s not messing anything up other than the fact that undo-ing doesn’t bring it back down to earth. It sorts itself out if I click “Reset Appearance”. It also happens if I opt+cmd+left/right on other dynamics, but only in certain places on different staves. It’s a fun little game to try and find the trigger points!