@schulte.thorsten.74 Thanks for reporting the problem. When you add the podcast, do you add by the URL or do you search? If searching, what is the search string you use?
If you are searching, try searching using only PodcastIndex 2.0 and see if it returns the right URL (not the one with proxy)
When you say one day it returns not found, do you mean a new episode cannot be downloaded or streamed? Or do you mean the feed update is showing not found?