Empty rehearsal mark not deleted after entering a line break.
1) New score
2) Any measure --> New rehearsal mark.
3) Enter to enter a line break.
4) Delete the line break.
5) Click anywhere
Expected: The rehearsal mark disappear because it is empty (like it usually does)
Even more important maybe: If you enter something like "A" and then remove that line break. There is still space added below the A. Which makes the A not vertically centered in its box.