So unfortunately it seems as though this is an issue with the beta launcher.
I have two accounts- it worked for one but didn't for the other. When I switched it back to the non-beta version of the launcher everything worked again.
So essentially there isn't much you can do about the issue unfortunately, I'd imagine uninstalling and reinstalling Minecraft would work, although that's kind of a pain. (If you do this be 100% sure to backup your world saves and all that)
Maybe send Mojang a message, or just try to wait it out. I'm sure they'll patch it soon.
