Last report, MC-217153, got closed as a "billing issue" when in reality this is a launcher problem, not a billing or account issue. Please fully read this before marking this as invalid.
The launcher is not properly authenticating. I have ruled out an account issue due to me being able to edit my skin and download the game on the website, and login on the old launcher and 3rd party launchers. The launcher seems to believe that my account is in fact 2 different accounts, and due to that insists I don't actually own the game. Same email, same username, same password, but the launcher says it's two accounts. Recently got a new router, Netgear Nighthawk XR500, if that helps with anything.
Hi, this is actually a duplicate of MCL-16570. Please see the Mojang Notice on that ticket for a potential fix to your issue.