No audio on iPad with first episode of series

ios

#1

I added a new season of a series to my plex library and only the first episode has sound on my iPad, no other episodes do.
When I watch those same episodes on my pc in the plex web app, all of them have sound.
The only difference I noticed when in the information tab was that the first episode had 'Audio profile' as "lc" while all the other episodes had "main" as audio profile.
They also didn't get matched at all like other seasons from the same series so there are no episode titles and episode "screenshots" as a thumbnail, even though I always add them from the same source in the same way.
When I tried to convert one of the episodes to 'Optimized for mobile', the optimized version did have working audio on my iPad.