Does not work with https://mods.factorio.com/mod/QuickMapTag
If I add the name with prefix (via the quick map tag dialog), and check the list - nothing changed.
Even if I re-open the tag (the normal built-in tag editor), add some letters - nothing changed.
But, if I remove TODO prefix, and add it again (in the normal built-in †ag editor) - it works. Annoying.

Better way to fix:
1) add some workaround for the mod
2) even better: add some "Refresh" btn to the TODO list dialog - recheck all tags for their names (it can help with other mods too)

For now I have added a console command to do this: /refresh-my-todo-tags

//EDIT: I should note I will also see if I can get the time and investigate WHY QuickMapTags does not work. Because the symptoms you describe seem to very much indicate a bug in Fox TODO, rather than a quirk of the mod (as if it was a quirk of QuickMapTags, it should work after renaming the tag in the built-in editor...)

sorry it's my bad.
I have changed some code inside it for tests...

[not a bug]