After PMS upgrade, ROKU player cannot play mkv files containing subtitles if selected

Server Version#: 1.43.0.10162
Player Version#: Roku Plex Preview Version 8.6 build 7

After upgrading my PMS to version 1.43.0.10162 while Roku Plex player stayed on the same version, any movie using MKV container with subtitles crashes the player. Using subtitles outside the MKV container appears to be fine, as in external *.srt file. However, the moment MKV subtitle is selected, the on screen wheel spins to about 33% and I get an error that the file could not be played/read or something this this effect.

It appears that some changes that were placed to the latest PMS are affected the Roku Player. Anybody from Plex cares to comment on this?

By the way, the files play fine in the web version of Plex player and JellyFin has no such issue either.