The latest SteamVR update has changed something in the way the Index controller work. I have tried to fiddle with binding settings but have found no solution for this yet.
Earlier I had to squeeze the grip to pick up grabbables and stop squeezing to release them. Now I already pick up a grabbable when I have two or more fingers touching the grip and to release I have to lift all my fingers. This is very annoying and makes objects feel sticky.