Problem FBX

Hey guys when i import a object from Blender it’s look like this.
We can see like 2d.

Yea very difficult to explain, just look the picture.We can see inside the axe.

sorry did not get your question

oh I see…

your surface is missing right?

What you’re experiencing is called a one-sided polygon or known by the term of ‘faces’ in Blender. You will need to flip those polys in Blender and re-import the model.
A small doc for your help

Ok thank you !

Select the model in blender go to EDIT MODE select everything then push CTRL+N and recalculate outside. As A Gupta said you need to flip your faces.

looks like inverted normals to me.