Hi guys, I just wrote an article about a problem my team and I have been facing recently after we 
reorganised our Figma component library (like adding new variants, deleting old ones, renaming things, etc)
We found that some of the Theme variants were stubbornly stuck with an annoying gremlin icon and to “fix it” we were having to import all the components back into the file, no need to say it was a nightmare!

I found an easy fix to it and you can find it in this article, it worked for 98% of our design files, the ones it didn’t unfortunately we had to swap them manually, however it still saves us a ton of time :
https://medium.com/@anna.massad/fixing-that-pesky-%E2%84%B9%EF%B8%8F-error-in-figma-fast-and-friendly-517d3351ef51

Hope it helps you guys!