Crash when changing voice of chord with tied grace note
The minimum requirement I have found to cause the crash is a chord with 2 notes and 3 grace notes (of any before variety) which are not a chord with 2 of the grace notes tied to the main note as in this picture
Select the chord (one way is to click a main note the shift+click the another main note) and change voices (I always press ctrl+alt+2 in my testing).
Result is a crash.
I suspect this is related to #298849: The 2nd note in a passage of grace notes will not tie to the main chord since there is a second note that is successfully tied to the chord. Because of this bug, the easiest way to add these tied grace notes is to start at the top, add one grace note, tie it, add another adjust the pitch, tie it and so forth.