Welcome to the Lightroom community. I'd love to help you figure this out.
Have you tried using a different SD card temporarily? Do you use USB hub extensions? Could you please share a screenshot of the import settings you are using? What specific version of macOS are you working on?
Try the import operation with the following suggestions:
- Copy images on the internal drive manually using the Finder first & then try to import.
- Try to plug the camera directly into the machine instead of the SD card.
Let me know how it goes. Thanks!