Bug report: Playback broken for acciaccatura on first measure

I'm writing a piano piece with the latest stable release on Mac, and I placed an acciaccatura on the first measure. Strangely, on playback it sounds as if the acciaccatura completely replaces the note it is attached to (in the example below, both triplets would sound identical):

The problem does not seem to occur with 16th or 32nd grace notes.