Rigging Issue - Automatic Weights not working

Link to Blender File:
https://drive.google.com/file/d/1LoEbuEF8Own63fXieiqXFntlqMx-6C21/view?usp=sharing

Can someone take a look at this issue and determine root cause and solution:

Issue: After parenting mesh to armature (with Automatic Weights), the model is not deforming along with the armature (vertex groups get created but no vertices get assigned to them)

I have the model (realistic human character, all one mesh) and a simple armature that I’m using just for practice. When I parent the mesh to the armature, and choose Parent with Automatic Weights, it creates the vertex groups, but no vertices from the mesh get assigned to the vertex groups. Can someone take a look and see what the issue might be? Blender file link below.

To reproduce the problem: try to parent the Body Mesh to the Armature, with Automatic weights, then try to rotate the thigh, for example. The mesh does not deform with it. Under the mesh’s data properties you will see the vertex groups but there are no vertices assigned to them.

What’s the scale of the mesh and the armature?

Hi, the problem is not the body mesh that works fine on it’s on. Its the dense mesh on the gums teeth eyes eyelashes that need fixing they give a Bone heat warning. The gums and teeth and eyelushes can be parented to bone instead.