I've got this problem too. Podcast functionality is a complete joke right now. Maybe actually fix the UX instead of giving the completely generic "please ensure you have updated to the latest version of Spotify... blah blah blah off and on again."
Clean reinstall works only for couple days, after few updates the problem returns and the podcasts stop updating again, only if you close and reopen the app the new podcasts episodes appear again, or do a clean reinstall which is a pain the ass because most people don't know how to do that, it does not work by only moving the app to the trash bin you need a cleaner app for that.
The mac app version is the worst and Spotify needs to focus on that, the app does not update podcasts also does not check played episodes as played (only on iphone app this works) also we aren't able to set the episode as played on mac version. I'm going back to itunes to listen to my podcasts.