I get Lumetri errors using my own LUTs as well, and I'm just navigating to my own folder. I didn't load them into any Adobe folders. I also really wish there were a standard location or a way to go through my own as easily as I can go through the defaults so I don't have to go through an open dialog for every one. I still can't believe that hasn't been added in all of these versions with Lumetri.