I’m aware of the “gotcha” when you open the footprint editor from pcbNew. But, I’m not doing that.
I can see the 3d model in the footprint editor, and when I update footprints from the layout editor it says it’s updating from the expected footprint library. Yet, the 3d model does not show up in the 3d viewer:
If you added the 3d model to the footprint in the Footprint Editor after you already used it in the PCB, you have to resync the Footprint in the PCB Editor to the Library version of the Footprint
And make sure the update 3d models checkbox is set
(Right Click on footprint in PCB > Update Footprint)