When trying to find visual filters in the visual filter menu, the search box is case-sensitive, so 'nt' won't find "NT". I would expect the behaviour to be insensitive to case.
I can't recreate this behavior. Can you post a screenshot of the two filters? "NT" and "nt"
I can't recreate this behavior.
And now neither can I. Either Logos or I obviously had a temporary blip. Probably me. Sorry!