I've been using JW for my Roku feed for a couple of years now...no problems. I added a video today like I usually would and suddenly have:
The feed format is invalid. We are unable to parse it.
I've tried re-uploading the newest video with a shorter filename...changing the title to remove the atypical character "|" (character above the forward slash. Still...feed won't work. Feedbucket has no problem reading the feed.
I actually didn't do anything new with the feed...just been using the one from my JWPlayer account since I created the channel. I've never had an issue before. This came up when I added the latest video.
With no changes on my part to the feed, I plugged the feed format I had been using https://content.jwplatform.com/feeds/bvnULZlM.rss into an unpublished channel on my account. A few minutes later, it checked out. Went back to the published channel...and the feed shows working. I have no explanation. Maybe there was a problem on Roku's end? Time lost, but it's working!