I’ve noticed this for awhile but never reported it. In the Android app if I have a feed muted and tap on it to view the feed, then the stories from that feed will be displayed when I tap on the folder to view all stories in the folder.
Clearing cache and force stopping and restarting doesn’t fix it. Eventually things “refresh” and those stories disappear from the folder view. It’s not a huge issue, but seems like a slight bug so since it just happened again I thought I should report it.