Video crashes with subtitles

anyone experienced with adding subtitles to videos? I have a video, everything works just fine. Video plays great, subtitles shows correctly but the game crashes after playing the video. This happens only if i add subtitles to the video file in MKVtoolmix. Without them it doesn't crash. The subtitles work though and are shown correctly in the video.

I'm using .srt file for the subtitles. Tried using .ass but these won't show in the game.