After Importing from camera card to LR the Grid view is not accessible. When I select Grid view in LR Library Module, the images appear to be in the format used by Apple Photo in their import window. (A single image on a white background with sequential numbers in gray at the corner) I noticed Photo was open behind my LR window after I had imported images. My entire library has now taken on this single image format in the Grid view.
It could be possible that the thumbnail slider size is set to high and that is why it shows single image in the grid view.
click on view menu and choose show toolbar to activate toolbar.
Look for thumbnail slider in the toolbar and reduce the size of the thumbnails.
If that does not help, would request you to share the screenshot of your Lightroom Library module for further assistance.
Glad to know that.
Thank you for your patience.