Whenever you import into Blender a Mixamo animation as FBX (for some reason it works better than the Collada imports) and export it to glTF, the entire model is gone when opened in Godot.
This is because Mixamo's FBX export has a naming convention using ":" in their bone and vertex group names, and Godot doesn't like that.
When you've imported your animations into Blender, you can run this script to fix the problem by removing the prefix on the bone and vertex group names:
import bpy
for obj in bpy.data.objects:
if obj.pose != None:
for bone in obj.pose.bones.values():
bone.name = bone.name.replace("mixamorig:", "")
if obj.vertex_groups != None and len(obj.vertex_groups) > 0:
for vertex_group in obj.vertex_groups:
vertex_group.name = vertex_group.name.replace("mixamorig:", "")
