The projector is smart. It is NOT 3D content. It’s just specially formatted 2D content. Each half of that picture contains half of the 1080 resolution (one for each eye) and the TV put’s it’s back together to make one frame that is stereoscopic.
My suggestion is to find out how to put that projector manually into 3D-SBS mode. If it’s actually a 3D projector it should have that option. I have a BenQ 2050 and I can put it in 3D mode manually.
As for your headline:
“Getting 3D (Blu-ray 3D-MVC) To Work On Plex”
Plex is not capable of playing 3D-MVC. Believe me there is a small but noisy contingent of folks that want this feature, but Plex doesn’t care. It takes special software drivers, capable hardware etc to do it and Plex doesn’t seem interested.
There are proprietary boxes like the Popcorn Time stuff that will play it (supposedly…never tried one) but at this point the only common solution for playing MVC is the free, LibreElec:
However, it is based on Kodi, not Plex. It does work though. I have a Pi3B+ running it and it will play 3D-MVC, or either of the half-resolution formats like 3D-SBS/3D-TAB just fine. I simply DESPISE Kodi’s interface so 99% of the time I just rip my movies into TAB/SBS and watch them in Plex even though that method is technically inferior. My old eyes don’t care enough about the difference to make it worth fighting with Kodi anymore.