Incorrect display of my 3D model with Panda3D

Question

I'm trying to use Panda3D to make a 3D game with Python. I used Blender to make a 3D model for the player, and gave it some animations and a green texture. It looks like this:

Then I exported it in .gltf Embedded, using default presets.

Finally, I tried using this code to display the model:

import panda3d.core as p3d
from direct.showbase.ShowBase import ShowBase
from direct.actor.Actor import Actor

class Game(ShowBase):
    def __init__(self, model_path):
        ShowBase.__init__(self)

        # Load my model
        self.player = Actor(model_path)

        # Add player to scene
        self.player.reparentTo(self.render)

if __name__ == "__main__":
    model_path = "player_model.gltf"

    # Create the game instance
    game = Game(model_path)
    game.run()

However, the model looks completely wrong:

I also get these warnings:

Known pipe types:
  wglGraphicsPipe
(all display modules loaded.)
:Actor(warning): player_model.gltf is not a character!
:linmath(warning): Tried to invert singular LMatrix4.
:linmath(warning): Tried to invert singular LMatrix4.
...
:linmath(warning): Tried to invert singular LMatrix4.

How can I fix the problem? Is there something wrong with how I am exporting the model?

I was able to import a basic cube model with the same process and got the expected result. Is the problem perhaps caused by armature or animations?