If you are not tied to Express VPN, try NordVPN. I have not had any issues.Thanks. I tried using San Francisco and LA but no go. Also tried using another (new) account with different email address after signing out of the first one.
I sent a message to ExpressVPN and waiting on reply.
Also did Google search and found a UK site (PixelPrivacy) which gives ExpressVPN its top rating for accessing Prime Video in 2020!
I'll try later as you suggest.