I installed stremio and mx player on my phone and enabled the foreground app setting, opened stremio, picked a movie, as soon as it started I clicked the cone on the top bar and immediately a lower bar opened with all my players there to choose from. Soon as I can I’ll check the 4K Max.
Ok so I did the exact same thing on the 4K. Enabled run as foreground, restarted Stremio as per pop up. Loaded a movie, selected a source, as soon as it started I clicked the pylon on the top bar using the 4k remote and also tested with the wireless keyboard and my list of players came up and I could choose MX Player Pro. I found 3 subtitle addons. Only open subs looked good I’ll check the catalogue
https://4b139a4b7f94-wizdom-stremio-v2.baby-beamup.club/
if you do a search for “titlovi.com subtitles” in the addon search field and then hit search it will also vome up to add.