When you use 'Use selected action', it brings up the context menu that is usually brought up by scrolling your mouse wheel. It did not do this before. This is a hassle for people that tend to use their 'optic' action or 'fire' action on the same key as 'Use selected action'. So if you share a key with anything else, it will bring up the context menu when you don't want it to, before it did not do this.
This started happening on today's patch on December 1, 2016. In my opinion it should have stayed as the old way where 'select action' would not bring up the context menu.