Cannot enter unison notes via mouse

1. Open drumset score.
2. Click on stave.
3. Enable 'Note Entry'.
4. Click on a note in the drum palette.
5. Click on the stave.
6. Click on the same note.

Expected result: Note is entered unison.
Actual result: Nothing is entered.

Workaround: Enter note higher/lower and move it.

Note: Also applies to standard staves.

Using MuseScore 2.0 Nightly Build 32fe6c4 - Mac 10.7.5