Same issue here.
In my case I think that the updating library simply doesn't work correctly. I checked the list of podcast through the Storage setting and could only see 3 out of x podcasts. For these I had an information of the space they take, for the others the space used is called "Document & Data" (some 1.3GB in total).
Not sure yet if I want to go back to reset the app as it would mean to search for the podcasts I set up all over again ... and too bad to say .. I can't remember them all (guess I might consider that those I don't remember were not worth while ;-)) ...
anyhow, until no overcast, soundcloud are interesting apps, but they don't do the things I liked about podcast (i.e. the sleep timer)
And thanks to all of you posting the direct feedback links to apple ... I usually try to avoid them as I find the support pages pretty much useless / counter intuitive. So your links helped to add to the feedback 🙂