Currently on Firmware 1.2.29 and only having the X20 for just over a week, it looked like there were no problems with Forced Subtitles in MKV Files from DVD. I only had a handful of MKVs and must have been lucky. On playing around a lot, I've realised the X20 must have Subtitle Track Memory and it remembered the last Subtitle Track. On renaming the MKV File, although the player respected the Flag to select a the sub, it selected the first sub in the list (wrong) and not the Forced one. But after that, remembered. My other mostly linux based players, do not have this problem. Personally now found a workaround that works with all, including the X20, as a temporary measure to suit all. Either set in MKVToolNix Forced Sub 'Yes' and Default 'Yes' and move it up to the top of the sub list. or Set in MKVToolNix Forced Sub 'Yes' and Default 'Yes' and remove other subs if not required. The the X20 can't help but get the right one then. Running through MKVToolNix after MakeMKV also fixes Chapter change problems, possibly an initial MakeMKV problem and MKVToolNix happens to fix it. Again, I consider this a workaround and not a fix. Basically, the player is respecting a call for a Subtitle from the Flag, but always selecting the first in the list, instead of the assigned one, unless otherwise told manually. Hate the term really, but sounds like a Bug to me.