Nothing yet. The latest #0717 build from Milhouse did play the 3D video (which is an upgrade from LE 9.2.3 which crashed), but the display is still showing two images.
So that sounds as if 3D MVC decode is working, but not being output as frame packed 1080p24 (i.e. not outputting it as 1920x2205 with 45 lines of blanking between each eye feed).
Does the Pi 4B output frame packed 3D when converting SBS and TAB for output as frame packed?