Could you try the following?
- Create a custom rig for your humanoid model. You can do this by clicking on the 3d model of the character. In the inspector go to the “RIG” tab and in the “Avatar definition” select “Create From this model” instead of “Copy from other avatar”.
- Check the animator component on Player/GFX, and see if the “player controller” and “avatar” slots are both occupied. In the avatar section you can now put the new avatar from step 1.