My TV also doesn't have an eArc, so i use this OREI 4K@60Hz 4x1 HDMI Switcher,... https://www.amazon.com/dp/B07XKBR79W?ref=ppx_pop_mob_ap_share and then enable pass through on my ROKU (which is where I play my Plex from) ... now pretty much all audio plays properly for me. I have the ROKU going to that orei hdmi switcher/audio extractor, then the eArc on that out to my soundbar and another hdmi out to the tv. Occasionally have to force direct play on my ROKU, but 99% of the time it works :)