I had the same problem until I realized the real problem was something else. What you're seeing in TT RGB Plus (screenshot and video) doesn't mean the fans haven't been detected, it means they are deactivated in the user interface. If you click on the little red circle to the left of the fan name, it opens the configuration interface. In the same way, if you click on the little green circle next to the fan name on an open interface panel, it will close it.
So far, so good. The problem I'm having is that the same two fans are always deactivated again (red circle, config panel closed) every