This problem is described in [this six-year-old question], which is apparently locked, and it still exists in SolidWorks 2022.

In summary:

When opening STEP files, there's a good chance that some internal shapes get moved around in the result. In my particular use-case, the .STEP is a model of a PCB with components exported by Altium Designer 22. All of the component bodies that exist as separate entities