I am experiencing a similar problem. I tried to use my offline mode (I have pandora plus) and the only station that worked was thumbprint radio. I worked through all troubleshooting options and tried to redownload my stations, but have had no luck. In hopes of solving this issue as quickly as possible and because I have noticed others being asked these same questions:
Pandora version 2203.1
Any guidance would be much appreciated as Pandora Plus does me no good to pay for if I can not use it for it’s intended purpose.