It seems like the hitbox for the Lock button has been increased significantly. I'm running ST on a Win10 PC. I can click up to 2 cursor lengths outside the actual lock symbol and it will still hit the lock.
This is super annoying when I'm quickly selecting items to populate my racks - suddenly they disappear and I have to go and search to find and unlock them.
I think the lock symbol itself is big enough of a target for clicking if I actually want to lock an item.