This only happens if you have no wave tracks.  Investigating...

Fixed in https://github.com/pokechu22/audacity/commit/ceef40d50.  Note that this fix may depend on some of the prior commits; I'm not completely certain (I think the only one that would matter is "Remove MIDI-only playback (without portaudio) logic", which PRL has merged, but I haven't tested).

Thanks for the quick work.  Rebased onto master here:

https://github.com/audacity/audacity/commit/03f9592f589a9baee52cde415d8fbb85e3afb1b9

I tried it, and it works for me, even omitting your other intervening commits related to scrub and seek.

Testing on W10-CE audacity-win-ra9a6f01-2.2.0-alpha-18-jul-17

With all three shortcuts B, C, 1 

a) the playhead disappear as it should on completion

b) editing is not disabled.

Looks to be ok on Windows.


Note the th2 "1" shortcut for Play one seconfd is no longer in the Standard shortcuts for 2.2.0 and thus must be user-enabled.

Testing on Macbook Sierra 10.12.5 with Cliff's 19Jul17 build

I can go through the motions of playing MIDI on the Mac - the playcursor moves appropriately but still no sound comes out.

With this limited testing, as on Windows

With all three shortcuts B, C, 1 

a) the playhead disappear as it should on completion

b) editing is not disabled.

So I'm thinking this is probably ok on Mac (but would prefer a retest by someone who actually hears MIDI out played on their Mac.

(In reply to Peter Sampson from comment #5)
Well after a long bout aor arm-wrestling with my Macbook I finally managed to wring some MIDI sound out it with an Audcaity Note track.

Testing on macOS Sierra 10,12,5 wuth Cliff;s 22Jul17 build

With all three shortcuts B, C, 1 

a) the playhead disappear as it should on completion

b) editing is not disabled.

So I'll mark this as ok on Mac

I can confirm OK on Mac.

Commit id 00f6ee.

RESOLVED QUICKFIXED
Tested and works on Windows.

Tried a few other things, such as loop play, and as a result created Bug 1707