I have a listing under “top window titles” that has a time total but no title. I think I can see which category it’s being counted as (one category is reporting about the same amount of extra time), but I have no way to tell what it is or how to remove it from that category. It is also not listed under “uncategorized”.
I removed keywords one at a time and discovered the problem is Notezilla; the individual notes don’t have page titles. I’m “solving” this for now by just removing it as a keyword.
update: of course now it just throws it into uncategorized, but at least that’s less problematic.