The third bullet point of four, fixed in my fork:

https://github.com/Paul-Licameli/audacity/commit/6252cd27f03a1ef33a18e650d822c051c7e5e1fb

I cannot reproduce the other three problems.

Pushed to master at https://github.com/audacity/audacity/commit/ad586b3e6991b62f3c25ecf129a86f82580d035d

Peter, I see you changed Release Note, just to say "Multi-track" instead of the old term "standard."

Lately though I fixed the third bullet point in 2.1.3.

Is Bugzilla intended to contain correct release notes for 2.1.2 or only the notes for the future release?

I just observed this:

In multi-track (formerly "standard") mode, shift-click on the Mixer board's Solo buttons behaves no differently from click.  That is unlike the track control buttons.  But in Simple mode, mixer board does respond to the shift key.

Mixer board should instead respond consistently with the track panel to shift-click, in either mode.

Part of this release note was just removed by Gale, because James reported that 735 does not reproduce.

Are you, James, now examining the other linked bugs?

Re: Comment #5:
Best asked (and answered) on quality email list.  The quick answer is 'no'.

From release notes:
* If you change the meter range in Preferences this is not reflected in the Mixer Board meters until restart.

Believed fixed by the fix for 745.

* '''Soloing or unsoloing a track in Mixer Board when in "Multi-track" Solo button mode''' may not immediately update the Solo button or waveform greyed/ungreyed state in the project window. 

Believed fixed by the fix for 509.

I removed this from the release notes:
'* If you change the meter range in Preferences this is not reflected in the Mixer Board meters until restart.'

My testing on Windows indicates it is now fine.  I believe I accidentally fixed it by this commit, which causes MixerBoard to be recreated on closing preferences.

https://github.com/audacity/audacity/commit/86901a00a1aa08051c6c19a5da20aa3fce3b3ccc

See the comment on the commit, and the new function RecreateMixerBoard().

I will be testing this on Mac and Windows - as James' Comment #8 indicates this may no longer be an issue

(In reply to James Crook from comment #8)
>Meter range does not reflect a change in the dB range meter preferences until restart

This now tests ok on both the latest Windows andMac nightlies

RESOLVED FIXED

This was a summary bug for Mixer board issues.

However, it only has one live issue left in it, which is Bug 289.  There is no active onward development of Mixer Board, so we no longer need a summary bug for Mixer Board.  Bug 289 on its own will do fine.  I took Bug 289 out of the dependencies and moved it to 'see also'.

Peter's comment #10 indicates that the issue fixed in the commit for comment #8 has now been tested OK.