In Grid view (just upgraded to 2015.8 and optimized my catalog) I am getting some serious anomalies with selecting photos, such as:
1) When a photo is selected by clicking, the photo next to it is automatically selected about two seconds later. The border of the photo that was actually selected now goes white, indicating it is the current photo, and the one I didn't want selected is grey. Lightroom shows that 2 photos are selected.
3) When another photo is clicked (without modifier keys) the first photo is deselected, but not the second (the one that was selected automatically).
4) I can keep selecting other photos and the one I didn't want selected stays selected.
5) If I have multiple photos selected, and I CMD-Click to deselect until I have only one left selected, at this time the photo adjacent to the one selected photo again becomes automatically selected.
6) Sometimes when I select the first photo this does not happen (i.e. the photo remains the only one selected). But in this case when I select any other photo (by clicking without a modifier key), the first photo remains selected. I can continue to click other photos, and the first photo remains selected, while the other photos clicked get properly deselected.
This does not happen all the time, but most of the time, and obviously results in me tagging some photos with the wrong title, keywords etc. It occurs with or without filters turned on.
Are you using a Mac Notebook or iMac with a Apple Magic Mouse? If you are then it has something to do with either the track pad on the notebook or the Magic Mouse. Or it is some type of Mac problem.
I can't reproduce it on a Windows 7 desktop or notebook using a Logitech Anywhere MX mouse or the track pad on my Dell notebook.
I restarted Lightroom a couple of times and the problem remained, but when my iMac crashed (which it does frequently, another problem) the problem went away.