In case you have corrupted the file I have attached another one.
Have you used Effect > Add / Remove Plug-ins…? Use that, select the acx-check, click “Enable” then OK.
If that does not help, do you see any of those other Audacity plugins such as Adjustable Fade or Crossfade Clips in Audacity’s Effect menu, or Beat Finder in the Analyze menu? If not, make sure at Audacity > Preferences…, Effects section that the “Nyquist” box is ticked (checked).
And if you still see no plugins in Audacity after that, try this: https://forum.audacityteam.org/t/nyquist-effects-missing/43925/9
Gale
Acx-check.ny (9.01 KB)