3rd Party Audio Effects (Plugins) Not Working.

I've been using Gullfoss and Fab Filter plugins in FCPx for a couple years now, and suddenly they are not working. I am getting an exclamation mark icon next to the plugins in the audio effects inspector tab. Does anyone know why this may be happening?I've tried reinstalling the plugins with the latest version to no avail. I'm on the latest FCPx: 10.5.2. I'm working on the latest fully specc'd iMac and on the latest OS: Big Sur 11.2.3.

I was able to use the plugins in Logic and other programs. FCPx seems to be the outlier.