Does anyone know what's wrong with my avatar upload?

>Avatar visible in unity, but invisible in-game
>Avatar falls through the world in-game
>Rotating the camera causes rotational displacement in game, as though pivoting around something, even though everything is centered in unity
>No scripts or weird shaders
>Some warnings about bone parenting, but I don't see why they would cause this issue

Possible weird things that might affect it
>The model was imported into blender as a gltf and exported as an fbx
>In the blender file that is imported, usually the object prefab named after the fbx file has the armature, body, and avatar as children. However, this has no body and instead the skinned mesh rendered component is attached to the object named after the fbx filename
>Deleting the skinned mesh rendered and adding my own body object with the skinned mesh rendered didn't do anything (although the prefab of the model was not changed)

Anyone know what's going on? I'm just trying things at random now, since the VRChat documentation does not mention this.