It all comes down to the url connection string. If the main list populates, but episodes don't, some sort of pathing in your URL is the issue. What is your primary connection string?
If you're familiar with Burp Proxy, you can use it to find out the exact URL that's being called when trying to fetch the content. And the raw request and response. Perhaps that will shed some light on the issue.
I've used Burp Proxy, and I've found that for episodes, it appears to be requesting the URL '/api//episode?seriesId=44', and '/api//episodefile?seriesid=44'.

The double slashes are not a typo, they're actually in the GET request. That might be the issue.