[UPDATE]
Thanks again for your patience while we worked on getting access to the Account Page working again. You can now log in and access website tools or any portion of your account.
We have received multiple reports of users encountering an 'accessdenied' error message or getting stuck during the sign-in process. Currently, this is not affecting our browser extension on YouTube, only tubebuddy.com and Account Pages (tubebuddy.com/account).
We sincerely apologize for the inconvenience and our Engineering Team is working on getting this resolved. We will post an update here as soon as the issue is resolved.