Problem: Simplify3D fill out tube model

Good morning,

I've a problem with my slicing program Simplify3D. I created a tube model with hexagon pattern on the outside with the model program Fusion 360.
But during the export from F360 to Simplify something bad happens. The slicing program fill out the tube without any reason for.
I never had this situation before and no idea to fix it. Are there any possible solutions?

Greetings

There is a setting in the slicer that makes models solid, useful if you have a bad mesh. It's a simple tick box but can't remember off top of my head what it's called

Does your wall have thickness? S3D may be calling this a solid object if it is only a surface without a wall thickness.
Not enough information to say for certain what is happening.

DLC

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