Changing the model of minecarts makes it invisible

[Joseph16]

I am attempting to change the look of the default minecart. I got the .b3d exporter for blender and have edited the model to my liking.
It's not a final model yet, this is just proof of concept. Now when I replace the default minetest cart model with this one, I get this:
How do I fix this?

[bosapara]

Show full init code with model and texture, possibly there are some mistake

[AiTechEye]

this happens if you exports the model in edit mode

[Joseph16]

How do I fix that? I’m a total noob with blender

[AiTechEye]

just exit the edit mode / tab button then export it,

this problem still happens to me