Enforce support for first n layers

[wbphelps]

Description of the bug

I'm printing an object with thin walls at the bottom and it keeps breaking loose. I read the description for "Enforce support for the first..." and it seems to be just what I needed, so I set it to 10. It added 3 layers of support at the bottom, not 10. I kept increasing the count and nothing changed until I got to 90 then it did create supports, but 161 layers worth.

Project file & How to reproduce

set "enforce support for first" to 80 and slice, support only generated for first 21 layers, and only on the outside.
change "enforce support for first" to 90 and slice, support now generated for first 161 layers, on the inside of the object...

enfoce support for error screen shots.zip

enforce support for the first n error.zip

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

2.9.2

Operating system

WIndows 11

Printer model

Core 1, MK4S