Play mp3 file as podcast on iPhone

I recently gained access to some bonus episodes of a podcast (Undisclosed) as a Patreon donor. I downloaded the episodes to my computer and can play them there, but would like to be able to listen to them in my car using my Podcast app (Overcast). I found instructions for doing this, but can't get them to work. I imported the files into iTunes, then changed the file type to podcast (from music) in the Info tab. Then I moved them to the iPhone (add to device). They show up in the iTunes podcast list for the phone, but they are grayed out and on the iPhone, they don't show up in the Overcast or Podcasts. Can anyone help? Thanks- Dave