Slicer adds a solid infill layer to a hollow area when importing STEP files.

Table of Contents

Description of the bug

When going to import a STEP file, the file appears to import properly, but when you go to slice it, the slicer adds a solid infill layer to a layer that should be hollow.

Left object, expected result (Object imported from an STL file.) Right object: STEP file version imported Object

Project file & How to reproduce

Body Tube Bottom STL vs STEP.zip

Steps to reproduce: Open the .3mf file and slice

Alternatively, I have included the STEP file and STL file so that it can be tested with a fresh import of the files themselves.

If you choose to import the files manually:
1: Import STEP file
2: Select Place on face and select the top face (This step is not needed as the issue still happens when you skip this step, but put here for completeness sake)
3: Slice

Checklist of files included above

[ ] Project file
[ ] Screenshot

Version of PrusaSlicer

2.5.0+win64

Operating system

Windows 10 21H1

Printer model

Ender 3