Final Cut Pro: Incompatible Audio Units Found - Force Validate Audio Units / Plug-Ins

 Mac M1, macOS Sonoma 14.3

Got an Incompatible "Audio Units Found" each time I launch FCP. In my case because of TC Electronic LM2n audio plug-in V1.1.4 which according to MusicTribe / TC Electronic is not compatible with M1.

 According to MusicTribe / TC Electronic V1.2.0 is compatible with M1s.  OK fine, I downloaded the correct version from this page. Search for LM2 and download V1.2.0, or the newest version.

I ran the Uninstall LM2n.command to get rid of the old version, and installed the new version. And I got... the SAME "Incompatible Audio Units Found" message on FCP launch! 😠

 Next I deleted Final Cut Pro Preferences (Launch FCP while holding Command + Option.) Clicked the Delete preferences button. And... SAME message. 😡 I guess this step is not useful.

Sticky, pesky message, even though I upgraded to the M1 compatible V1.2.0 of the Plug-In.

OK, so the way to do this is to force Final Cut Pro to rescan all Audio Units by clicking the "Validate on Next Launch" button in Preferences / General:

Click on Audio Units: Validate on Next Launch.

 Bizarrely when you click on this button, nothing happens or shows that it's being selected. But, on restarting Final Cut Pro, it DOES go through all the AUs and validates then. In essence it's instructing FCP to perform a force validation of AU audio plug-ins.

 And this time, lo and behold... They PASSED! And now I can use them in FCP, no problem.

 So if you believe you have the correct version of an audio plug-in, but FCP is flashing the message, do try the force validation as it might fix the problem as it did for me.