Deleting a bar causes slurs in following bar(s) to disappear
This happens when you are editing a score and have made parts from it.
If you remove a bar with Ctrl+Del, the slurs disappear from the bar following it (sometimes for several following bars).
To reproduce, start a new blank score, enter a couple of bars with notes and slurs.
Now insert a bar at the beginning and delete it (works fine)
Make parts: File, Parts, New all
Now insert a bar at the beginning and delete it (removes slurs in next bar)