Mkv file upscaling, language tags of subtitles are lost

Upscaling working fine but data lost when rebuilding mkv file container.

The language tag of subtitles is always lost in translation.

Sample tested using this public mkv test file:

Input mkv looks like this:

Output mkv looks like this:

This is a known issue that the team is investigating and trying to resolve that was also mentioned in the v5.2.2 release. They are still working on a resolution for it.