Playback of acciaccaturas on tied 16th notes is broken
Open a new score.
Add any instrument from the "Keyboard" category.
Set the soundfont to MS Basic.
Place a 16th note.
Tie the 16th note to a longer note.
Add an acciaccatura to the 16th note.
Press play, and the tied note will be shunted backwards in playback. The amount that it is pushed back depends on the length of the note it is tied to; several consecutive tied whole notes will cause the note to play multiple measures in advance. Any note shorter than a 16th tied to a longer note will also reproduce the glitch.
When using MS Basic, this only occurs with Keyboard instruments, but every external VST I've tested has had the same behavior occur. Muse Sounds appears to be unaffected by this glitch.
Attached is a score that demonstrates the issue.