This conversation has been merged. Please reference the main conversation: Lightroom Classic: Drag & Drop no longer works for import
My setup with photos is to cull and rate them all in Photo Mechanic and then import to LR. Sometimes if I only want to import a certain selection from photo mechanic, I'll select all the ones of a certain number rating from PM and drag them into LR. In that LR import dialog box, it will usually show all the photos in that folder and the selected ones (that I chose from PM) to import are usually the exact same selection.
HOWEVER, recently, when I bring in a certain selection of photos or even the entire folder's worth, it will all be deselected. Not a single photo selected and I don't know why.