Extended slur from grace note

Steps to reproduce:

1. Open attached score.
2. Double click slur.
3. Shift - right

Result: Slur extended onto the chordrest at second beat.
Upon save and reload, the slur is at the previous position.
The extend action cannot be undone. Tried with Ctrl+Z and Shift+Left.

Expected: No change. A slur should end at the chord rest right after the grace note.