i'm sure you did but just to double-check: you put your actual IP in there right? and are using host port 8080 to forward into the docker container?
if you have both of those set up that way i have no idea what's going on...even more so if the games are working. if the m3u is imported into channels and it's loading the games, the container is working so i can't see any reason the epg wouldn't work as well. if you go to that URL in your browser, can you see the epg xml? (you might have to do a view-source to see it formatted easily enough to read it)