It seems there is a filter bug for at least ‘is empty’ or ‘is not empty’ filters:
it happens when one deletes the option from the field edit menu of a single/multi select field.
also, column stats do not register these rows as empty (for the ones containing the deleted option)
the UI does not reflect that single/multi select state, so the cell seems empty to the user.
it seems a bit similar to
and perhaps
and
which might be a broader issue with is(not) empty criteria.
This is one of those issues we’ve been having with Baserow since the start of our tests - pertaining to lack of user trust - or rather - the lack of confidence that the platform displays what users expect when dealing with data analysis.
Hi,
Thank you for reporting this. I’ll created an issue: is empty / not empty filter does not work on deleted single / multi select options (#3053) · Issues · Baserow / baserow · GitLab
I don’t know how frequently you need to remove options from a single select or multiple select, but duplicating the field after the removal of an option and working on the duplicated field seems to - temporary - solve the problem.
The overall problem is that this is yet another workaround one has to remember - like I said in other posts - these small bugs accumulate and in total have an impact on UX and users’ trust in the platform. It took us a few weeks to pinpoint this after initial reports (which I initially thought were only related to an Airtable import bug which has, fortunately, already been solved !)
Anyways - thanks for the workaround idea and for your ongoing work on improving Baserow! 
I really appreciate it!
