Where are my MotionBuilder layers?

The Maya FBX Plug-in lets you import animation layers without baking them. Otherwise, the animation is baked into the base animation layer.

To retain animation layers as separate layers in Maya:

When you import an FBX file, disable the Bake Animation Layers option in the Maya FBX importer. See Bake animation layers

If the option is active, the plug-in automatically bakes the animation layers during the import process.