The documentation of TODO Explorer in both R# and Rider explicitly says that TODO items can be uses of NotImplementedException in code, and the TODO Explorer contains definitions that try to do this. But as far as I can tell, there is not actually a mechanism by which TODO items can be found in code at all. NotImplementedException seems to have been added to the TODO Explorer with the assumption that it could be found in code, but the TODO Explorer will only find instances of NotImplementedException in comments; IE: the TODO Explorer seems to be limited in general to searching only comments.
I notice that while there are many images in your documentation showing the default "\bNotImplementedException\b" pattern, there are NO images showing any results of this pattern.
I hope I'm just missing something, but otherwise it seems like you have some miscommunication in your team about what the TODO Explorer can and can't do.
(What annoys me about this is that this is not the first time I've went on a wild goose chase trying to find how to make the TODO Explorer find NotImplementedException, as it claims to. It's been this way for many many years at this point.)