3d models do not appear when convert

I always have problems when modeling 3D + Animation does not appear when the convert. whether there is a solution that + Animation 3D models become successful. I made a model using a blender. I attached an example file. Thank you

file_dae.zip (549 KB)

Thanks for the test case. Turns out this is a known issue in the converter (#283). Until there is a fix, you could either export the model without skins or use a simpler skeleton.