Muxing out Russian language ruins smooth video

[you-go]

I use MkvMergeGUI 7.6.0 "Garden of Dreams" in an attempt to get rid of Russian audio.

Under the 'tracks, chapter and tags' there are four boxes.
1. MPEG-4p10/AVC/h.264 (ID 0, type: video)
2. AC3/EAC3 (ID 1, type: audio)
3. PCM (ID 2, type: audio)
4. Subrip/SRT (ID 3, type: subtitles)

It's a whole series of files I wanna do.
For the first few files, nr. 3 wasn't PCM but AC3/EAC3, just as no. 2 above.
But ever since the files contain this PCM audio, after muxing the video doesn't run smooth any more.
The files prior to this file all run fine, smooth as clockwork.
It's probably an easy fix but I can't find it!!
Oh, and nr. 2 = RUSSIAN audio in this case,
Nr. 3 = ENGLISH audio.....

Anyone an idea?

[ndjamena]

We'd need more to go on, mediainfo, mkvinfo, ffprobe... there's plenty that can go wrong.

[jman98]

What are you playing the final MKV file on? PCs usually have fewer problems. I've seen BluRay and media streaming players like Western Digital have big problems when the audio or video is unusual for MKV. MKV basically allows anything inside it but devices that aren't PCs usually don't really support everything that is possible. Once I made an MKV file with Divx video, AC3 audio and MP3 audio and none of my BluRay, DVD or media streaming players can play it correctly. I had no problems playing it on a PC though. PCM audio is allowed but unusual for MKV and I could easily believe that a hardware device would have problems with that.