Occasionally (but fairly often) after dropping a humanoid game object in the Pose Editor the object will not get fully loaded. The object will take currently loaded clip pose in Pose Editor mode and will go back to a reference position in Config mode but no bones are shown and playing the animation in the Clip Editor won't have any effect.
Other than restarting Unity, what works is to change the layout so that Pose Editor and Clip Editor are closed and then switch back to the layout with both panes open. Generally, once the panes have been "restarted " the model is imported correctly.
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