I encountered the same issue and it was caused by Google's multiple sign in (on desktop browsers).
I was signed in to my corporate account which I had authorised for testing, as well as my personal account which was not authorised. My corporate account is set as the default account, however when visiting the Play Store it was defaulting to my personal account (maybe because that's the one I use on my Android devices).
The problem can be solved by either authorising all signed in accounts for testing, or by signing out of unauthorised accounts.