Podcast App on iMac stuck in "unavailable loop"

Ugh! I can't access my Podcasts anymore on my iMac. I found an old link to a 2012 video podcast. I clicked it, the app went to a full-size video frame (blank) and a pop-up came up saying "Episode Unavailable: This episode is temporarily unavailable." OK, fine. But when I dismiss the pop-up and click the red close button, it reopens within 2 seconds and the same "unavailable" pop-up appears! I can't stop this loop from happening! I've tried to quickly close the pop-up, and then quit the app. Restarting Podcasts brings me right back to the same blank video window and the "unavailable" pop-up. I can't access any other controls.

Any suggestions???!

iMac 2020; OS 11.6.5; Podcasts Version 1.1.0 (1575.1.2)