Have you tried deleting the reserved hard drive space for mods. Possibly you might have a corrupted mod download or something got corrupted. It should be in the section where you see all the games and then you should be able to manage Skyrim game and you should have an option to delete game save and to delete the mods as well.
I've never installed a mod in my life, so that's certainly not the problem. I've also tried deleting the reserved space with no luck, tried changing my DNS settings as suggested by Bethesda Support, but nothing helps.
Which user account are you using the one from bethesda.net
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Is the Xbox One updated as well as the game.