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.
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