I had the same problem of Mod Organizer not loading mods. Actually, it would not load ESPs, but textures would load fine. It took me ages to realise the problem - SymMover. I had used symmover to move the original Skyrim SE folder to another drive - windows still sees the original folder in the same place but the contents are elsewhere. It seems Mod Organizer does not work with this system, I guess because it virtualizes folders.