Unable to get subtitles streamed in MacOS -> Xbox/Panasonic

Apologies if this has been answered elsewhere but lengthy searching and googling has not led to an answer.

I am running Serviio on macOS Mojave 10.14.16
Servio Pro v2.0 Trial version

I am streaming to: XBOX One and Panasonic TX-50DX703E
I have selected a few titles for testing which include several .MKV files, several medium (3GB) size, one huge (9GB). Also an .MPG. All have .SRT subtitle files in the usual formats.
All titles work when played standalone from USB drive on XBOX (Using Media Player) and MacBook (VLC)
Subtitles play in all cases, apart from sometimes dodgy performance from XBox Media PLayer on .MKV. VLC on XBox plays these with subtitles (but itself is very buggy and the driver to my desire to move to streaming. Media Player is dodgy on subtitles, and in any case the XBOX can't take a >4GB file)

I have tried every permutation of settings - with Burned-in OFF and ON. Using UTF-8 encoding (default). Of course ENABLE SUBTITLES is checked
Language is set to only EN for the moment, for Audio and Subtitles

While the titles appear and play just fine (that worked without problems), no combination of filetypes/subtitles setting works for me apart from one: The JPG with Burned-In set ON plays on Media Player on XBOX. Nothing else plays the subtitles on either platform, burned in or not.

And to add a touch of mystery -- the 9GB MKV suddenly refused to play on the XBOX and would play without Audio on the Panasonic - despite the fact that it had played fine on both earlier (albeit without subtitles). I can only imagine this was down to local intermittent issues

Spent hours on this, have finally 'thrown in the towel'.

Can anyone shed light on this? In a muti-lingual household subtitles are essential, and without the ability to deliver these, this is a dead end solution (and back to buggy VLC)

thanks in advance
-gordon

[atc98092]

I have found that overall a lot of players simply don't handle SRT files well. I don't think it has anything to do with Serviio. My Roku devices are hit or miss, mostly miss. My Samsung TVs rarely display them, but then they are so bad with DLNA it's why I switched to external players years ago. In fact I've pretty much moved to the Nvidia Shield for its superior handling of all audio and video codecs, as well as displaying all of my captions, regardless if they're embedded in the file or via an SRT file. The Roku players are fine if captions aren't needed, or if the captions are embedded in my recorded TV broadcasts.