Trying to select photos to import

Did you recently update the system on your iPhone?

The upgrade to iOS 12 may have enabled iCloud Photos. With iCloud Photos enabled on the iPhone and your Mac all new photos taken with the iPhone will automatically sync to your Mac and all new photos imported to your Mac will automatically upload to iCloud Photos Library and to your iPhone.

• Check the Settings > Your Name > iCloud > Photos on your iPhone.
• Check the Photos > Preferences > iCloud in Photos on your Mac

Has iCloud Photos become enabled? If yes, do not delete any photos from your iPhone, that you want to keep on your Mac. And do not delete any photo from your Mac, that you want to keep on your iPhone. With iCloud Photos enabled, iCloud is trying to keep the photos libraries on all devices identical, and a deletion will sync to all devices.

no, do not enable iCloud Photos, if you do not want to sync your libraries on all devices and to keep them identical on all devices.

Do you remember, if the option "Optimize Storage" had been enabled on the iPhone?

The option to select photos to import should appear, when you insert a card into the card reader or when you connect an iPhone or iPad. Does your iPhone still appear in the sidebar in Photos when you connect it to a USB port?

I did what you said,

So, has iCloud Photos been enabled on your iPhone and your Mac?