SOLVED: Multipart episode not playing next part

[freegamer]

Hello,

I have a problem when watching an episode that is split in parts. The player automatically plays the next episode instead of going to the next part.
In the webinterface when you open the episode you can see the "additional parts", but it doesn't automatically play them when the previous part ends, but jumps to the next episode.

Meaning it goes from S10E09-part1 to S10E10 instead of S10E09-part2.
I have to exit the playback and select the next part manually if I want to watch it.

In the Swiftfin mobile app the additional parts are not shown at all.

Is the naming of the episodes wrong for this to work? I've read on reddit that apparently it should work and I'm using the naming convention from the wiki if I'm not mistaken.

The episodes are named:
Detektiv Conan - S10E09-part1.mp4
Detektiv Conan - S10E09-part2.mp4
Detektiv Conan - S10E09-part3.mp4
Detektiv Conan - S10E09-part4.mp4
Detektiv Conan - S10E10.mp4

Server Version: 10.8.13
OS: Linux
Install method: Docker
Client: Browser (shows parts, does not play them automatically), Swiftfin iOS (does not show parts)z

Webinterface showing the episodes parts:
   

Webinterface shows that it wants to play the next episode (S10E10) instead of the next part (S10E09-part2) when ending part1:
   

Thanks