How do I fix the 'Rebuild Errors' in SolidWorks when importing STEP files?

Whenever I import a STEP file into SolidWorks, I often get rebuild errors or missing faces. Sometimes the model shows gaps or surfaces that won't knit properly. What causes these issues, and what are the best ways to clean up and fix these imported models for further editing or simulation? I’m using SolidWorks 2022.
Right click on the "Imported" feature in your Feature Manager Design Tree, click on Import Diagnostics and make your selection from Attempt to heal all, Attempt to heal all faces or Attempt to heal all gaps.