Cannot create new tags

Hi
I created hundreds of tags in Darktable over many years, and suddenly I cannot do it anymore! I was on 4.2, and installed 4.2.1 to see if it would fix the issue but it didn’t.
I have a top-tier tag called Birds for example. I would right-click on Birds, and then “…create tag”. I will fill in the name and the synonym, and click on Save. The list of tags will then collapse, but my new tag will not be in there. What am I doing wrong?

I don’t see a button called “Save” but there is one called “New”.

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The db must have become corrupt. I solved the issue by rebuilding the database from the sidecar files.