Rebuild m2ts doesn't play - tsMuxeR GUI 2.6.12

[V!roX]

Hi everyone!

I'm currently working on translating a Blu-ray to German by replacing one language with another completely and dropping the modified m2ts into the BD folder.
Replacing the language on the main stream worked fine with tsMuxeR, but when trying to replace the subtitle on one of the bonus clips (720x480, 29.97), the video wouldn't show when playing the BD in PowerDVD. The timer works, but the video is black and there is no audio. When building a BD-folder with tsMuxeR and then also replacing the clpi with the new one, the timer also stops working.

I tried narrowing it down, I didn't change ANYTHING in tsMuxeR this time, so subtitles, no additional SEI/VUI data, no chapter markers.
Putting the remuxed *.m2ts into the folder gives me the same result.

I'm thinking I'm doing something wrong here, obviously tsMuxeR does change something that makes the file unplayable. Any advice?