Single sign-on issues are typically caused by the same credentials (e.g. username, password) being used on the same domain, e.g. amd.com. In this instance it seems likely that your AMD community sign-in is conflicting with your AMD account sign-in. I would suggest signing out of your AMD community account, and then signing into your AMD account. Clearing your browser cache or using a different browser might also be worth a go.
If the problem persists you will need to contact AMD to correct the issue.
Hope this helps.
