Rebooting makes no difference, Gale. I still have to use Terminal. And yesterday evening, the Terminal method 1 didn’t work, so I had to use method 2 [right click, open/show package, drag exe into Terminal]. I’ll let you know how things go. I have been waiting for a long time to get this working and now it is, I’ll be using Audacity a lot. Hopefully this bug can be fixed?
Or you can just double-click the Audacity executable in Contents/MacOS/.
We can’t fix the bug - if it is an Audacity bug and not a Mac bug - until we can make it happen on our machines or have some idea why it is happening. Are there still no messages in the Terminal when you execute Contents/MacOS/Audacity?
You could launch Audacity normally, triggering the problem, and then look in Console.app for reports or warnings that occurred just now.
Gale
I have exactly the same problem. Nyquist plugins did not load.
I clean install macOs Sierra last week on my 2011 iMac. All work fines with Audacity 2.1.x (tried first with 2.1.0, then with 2.1.2), except the Nyquist plugins.
I mount the DMG file, copied the entire folder into the Application folder, unmount the DMG file and run app from my hard-drive.
I got this in the log screen :
08:08:58: Audacity 2.1.2
08:08:58: Avertissement :Critical Nyquist files could not be found. Nyquist effects will not work.
So, I’m glad to have another Mac in my house… I did a test with a MacBook Pro 2010 with OS X 10.10.5. I perform the same install of Audacity 2.1.2 and the Nyquist loaded at the first start without any problem. (no log message about Nyquist)
I’m pretty sure it’s a path/permission issue with macOS Sierra.
I had the same problem. Macos Sierra “clean install”, which means Mac OS X internet install (Lion) then upgrade to Sierra.
I don’t have this problem anymore. Don’t know if it will work for others, but what I did was changing owner:group to admin:wheel (run in terminal: sudo chown -R root:wheel /Applications/Audacity/ )
Thanks for writing. What was owner:group before? Admin is not the same group as root so I don’t quite understand it as you wrote it.
Gale
It was myuser:admin. All other applications were assigned to MacOs defaults (root:wheel). I just changed Audacity to that owner (root) and group(wheel).
Sorry to post again, but since my comments are waiting for a mod to approve I had to post again.
I just re-read my post and where I said:
but what I did was changing owner:group to admin:wheel
should be read as root:wheel
My bad!
Forget about my suggestion about changing owner and group, it didn’t really worked (nyquist couldn’t load). I think I found why Audacity wasn’t working 
I deleted the old installation and ~/Application Support/audacity files. Did a fresh reinstall and, as expected, Audacity couldn’t find any plugins neither load nyquist.
All files in the Audacity app had the xattr com.apple.quarantine set. Even when I told gatekeeper that it should trust Audacity, it wont allow audacity to read nyquist and plugin folders. I tried to remove that extended attribute running:
xattr -r -d com.apple.quarantine /Applications/Audacity/
And now Audacity is working like a charm!
This worked perfectly for me as well. Definitely a gatekeeper issue.
Thanks, this was driving me crazy.
Cheers
Also have the same issues with LADSPA plugins not working on Mac OS 10.12.1 Sierra. The fix posted two posts previous seems to have worked perfectly.
I’ve just been testing with that latest alpha nightly ba263d0 04Dec16 on Sierra - and I can no longer see any Nyquist effects.
If I use Finder to look in Applications>Audacity>plug-ins I can see a whole slew of nyquist effects .ny
But in Audacity only the Audacity Effects are showing - and going to the Plug-in Manager there are no nyquist efeects cisible there at all - not in the enable, not in the disabled and not in the new. The new does have Classic filters and a whole slew of apple au effects.
Now I’m a very simple-minded Apple neophyte and expect all this Apple stuff to “just work seamlessly” as all my Macolyte friends have always assured me it does over the years. This seems to give the lie to that … 
If this is a bug that Apple has introduced with Sierra then we are going to need a nice simple recipe for our less-skilled Apple users like myself 
Peter.
Have you tried the Terminal command given here:
You just need to open /Applications/Utilities/Terminal.app, then type or paste that code. You probably need to prefix the code given there with “sudo” (without quotes), so
sudo xattr -r -d com.apple.quarantine /Applications/Audacity/
When the command is typed correctly. hit ENTER.
You will be asked for your password. Type it carefully because the Terminal does not echo the password to the screen, so you can’t see the password. When the password is complete, hit ENTER.
You don’t get any feedback for a successful command, so if you get taken back to the command prompt, that’s a good sign.
Gale
@Gale: I’ll give that a try when I get some time
But it doesn’t seem like a “simple recipe” to a Mac neophyte like me 
Peter
Let’s hope with the signed build that we won’t need to offer that solution. You can reboot, or execute the “Audacity” shell app inside the bundle, but it is said those methods are less likely to work.
Gale
Gale, if I did get time to try that non-simple recipe, would doing that invalidate any future test to see if the upcoming signed version supplies the Nyquist commands 
I din’t need the Nyquist commands there right now - so it’s no hardship to wait.
Peter
As long as you only removed the quarantine on /Applications/Audacity/ it would be a valid test to then download the signed build to your Downloads folder and execute it from there.
Gale
Thanks for posting this!
After running the command the nyquist plugins are working perfectly.
Just got a new Mac and thought I was going crazy!
And now Audacity is working like a charm!
I’m so glad to sound this post. The “xattr command solution” solved my problem with seeing the nyquist plug-ins. I spent a couple of days off and on searching for a solution stumbling upon this page.
To save others time, I suggest that you add some information to the Mac OS download page and if possible the readme included in the download DMG (thought this may require new build so maybe that’s not so easy). I see there is a “Known Issue” regarding security settings on the download page but the xattr solution is not shown and the one that is mentioned does not solve problem.
This is the OSX download page I’m referring to: http://www.audacityteam.org/download/mac/
Thanks. The problem is a Mac issue that only started with 10.12.1 and does not affect all machines.
The upcoming 2.1.3 release (which is planned for the 20th February at present) is signed with an Apple developer signature and should fix most of this problem, except for a much smaller subset of machines where the plugin failure (and also lost access to LAME/FFmpeg) occurs when closing project windows. The current status of this and other Gatekeeper issues will be in the 2.1.3 release notes, and Sierra will be described as “only partially supported”.
Extra information is already needed on the download page for 2.1.3 to describe how users should handle duplicate plugin entries from the previous installation of Audacity, which arise from Audacity 2.1.3 being supplied just as an application instead of inside a folder.
So very likely all we will do on that page is link to a help page about “Partial Sierra support”.
If you want to try the RC1 release candidate of 2.1.3 and give us feedback about it, please visit Audacity download latest version.
Gale
If you want to try the RC1 release candidate of 2.1.3 and give us feedback about it, please visit > Audacity download latest version> .
I tried the build and it worked perfectly. Its nice the way its a single package instead of a folder now.
Thanks!