In this example I'm importing two STP files received from the same supplier. For one of these parts, it was necessary to set the Scene Kernel to ACIS for it to import correctly, whereas for the other part it imported correctly when the Scene Kernel was set to PARASOLID. So even though these came from the same supplier, the CAD software used to create or export these may have been different. Hence the different results.
Malcolm
STP Import - Changing Scene Kernel - 20240504.mp4