This is probably a ridiculous question, but I usually stream from my laptop to my LG tv or my phone to any other tv, and I find that using my VPN keeps the casting output option from working. Like in Popcorntime, the Watch Now doesn't show my tv, only the laptop app or VLC. On my daughter's fire stick I can't even cast to it unless I turn my VPN off.
I don't have any problem streaming Plex or Emby from my laptop to the tv. Is there a way to cast without compromising my privacy?
I can't offer help on the issue, but as far as I understand there are no legitimate and safe versions of popcorn time anymore. The main version got taken down a few years ago iirc. There's still plenty of unsafe versions though. Might want to double check you got it from a safe source.
It might be easier for you to torrent normally while connected to VPN, then disconnecting to stream to your device.
I do that now.