New steamvr update made letting go of grip really weird in some games. It's an easy fix, I'm assuming it's due to them adding a new variable to play with. Just go into SteamVR controller settings and edit the "use as grab" on grip and then the gear icon. It'll likey have proximity at 0 for release. Move it to something comfortable to you; force 20 is mine. Of course, do it on both controllers. That should fix it.