Help: Subtitles not working on smart-tv

Recently i bought a second hand tv, the Philips 43PUS6162/12 4k (i know it a bit older but im on a budget). Ive installed the plex app, version 5.93.2 and everything seems to be doing alright.

Only thing i cant seem to get to work is the subtitles. Ive tried turning burn subtitles to always, ive tried different subtitles formats like pgs and srt, but none seem to work or even show up. They work fine on my phone and browser, just not the tv.

Does plex just not support it cause its an older tv (2019) or am i doing something wrong. If the answer is that it isnt possible, than thats fine too, but thought i would just ask in case i missed something

Thanks in advance!

What version of PMS?
What type of subtitles, internal or external?
What type of video container? MP4? MKV? AVI?
How many subtitle tracks exist on the video in question?