I had this same problem last week and the solution that worked for me is here:
https://community.roonlabs.com/t/metadata-improver-warning-adding-music-to-library-with-animating-circle-that-wont-go-away/110690/4?u=peter_duckworth
Ignore the bit about restarting the core, but follow the instructions under ‘clearing the roon cache’.