I've tried searching the forums for a fix, and I still can't seem to find a solution.
I upgraded to Lightroom Classic CC a couple weeks ago, and every time I've tried to import photos from my SD card, a few (not all) images are greyed out, with a tooltip box stating that the photo has already been imported. This clearly is not the case as the images are new. The issue still persists when I untick 'Don't Import Suspected Duplicates'. I've ejected the SD card, re-inserted it and tried again, with no success.
My current workaround is importing the images to my hard drive and then importing them into Lightroom, which isn't ideal.
Please describe the exact nature of the problem, and include details of the version of Lightroom and the OS you are using. The original question is 2.5 years old, so it's unlikely to be the same issue.