The "possible method call error" linting seems to have some difficulties at the moment, but it's not always quick or easy to come up with a MWE. Here's one case where I think I know the source of the problem:

In this case, categorical is simply re-exported from MLJ, so I think that's where the difficulty is. (I don't have any explicit using CategoricalArrays in my project...)
Thanks, that's really helpful (the clue to the issue is the 0 methods for function.. in the hover - we've found the symbol for the function but not the associated methods). I'll have look
I seem to be getting this while using Plots:

although the plot() works just fine. I'm guessing it's the same problem?
I'm getting it too with several packages, assuming it's a same problem.
Also, it happens to be for perfectly working code when I'm trying to parse JSON from external process:

It's also happening when I'm not doing anything reexported:

I'm also seeing this when using "Not" on a DataFrame object:
