UI Builder: USS not Loading

I can’t use this package at all because it just won’t load any USS from the file. It keeps having the error:
StyleSheet import: type=Semantic, code=InvalidURIProjectAssetPath file=Assets/Editor/Tagger.uss
Library/unity default resources
It is worth noting I am using this to create Unity Editor UI. It doesn’t matter how many times I restart, create a new USS file and adding the selectors to the file or change the UXML stylesheet path. It just won’t load the USS files at all (it keeps showing it as empty). Any suggestions?

Hello.
So do you have an issue with UXML / USS files create via builder or when trying to open existing UXML that was created manually?

Can you please share a sample project?