Looks like Bambu has screwed up the STEP file import process...AGAIN

I found a solution for this as I was having similar problems.
I adjusted the angulation and linear deflection up to have more tolerances.
And waited for the triangulation count … if it was over 700,000 it would just keep calculating ----- and not produce a model.
I’d suggest bumping these up on the scale … and wait for the triangulation count … then press ok.
3mf and stl files had way less model precision and I was making smooth curved parts … so needed stp file precision.

Best of luck.

Let us know how it goes.