Just to be sure about your import procedure: After you have seen the Photos in the "Imports window" that appears when you insert the card, did you select the photos for importing and click the "Import selected items" button and wait until photos gave the message "Imported ... photos"? The "Imports" window is just showing you the photos available for importing and expecting you to make a selection for importing. The photos will not be imported until you select photos for importing and start the import.
If you successfully imported them, the imported photos should appear at the bottom of the "imports" album in the sidebar and also in the All Photos album at the date set by the camera. You should not erase the card, until you have seen the photos in "All Photos" and checked, if they are readable.
You may want to check two things:
- The Photos > Preferences > General: is the option "Importing: Copy items to the Photos Library" still enabled? If you do not copy the items into the Photos Library, you must not erase the card.
- The date set in your camera, also the format. Is the date in the camera set correctly? Otherwise the photos may be sorted in your library at an unexpected date in "All Photos".
