Rehearsal marks display as empty boxes in parts until reload

Windows 7, GIT commit: 3543170

1) open attached score test_position.mscz
2) click a rest somewhere on second system of score
3) Press Ctrl+M to enter a rehearsal mark, enter term "A"
4) view flute part

Result: mark appears as an empty box
Expected result: mark appears as in score, with letter A in box

Save and reload the score, and the mark appears as it should.