Master password should work on all. Try changing the master, see if that works

Changed P/W to Pro series.  Tired that for client file.   Didn't work.

Reviewed 2019 client file.   Used a P/W i remembered which worked.   That P/W did not work in 2020.

??

Not talking about password to open PS, see this link to make you are setting it up correctly.

https://proconnect.intuit.com/community/manage-access/help/using-master-client-level-and-electronic-...