I also have the problem, it started either yesterday or today. With testing I could find out a few characteristics of this issue.
I own a 2016 MBP 15 inch (2.7GHz i7, Radeon Pro 460). The Problem only occurs when the macbook is running the Intel HD 530, ONLY if I am viewing a still screen. Even the tiniest animation in a webbrowser and it will not appear at all. Moving the mouse will also immediately fix it (until you stop again and wait a few seconds).
Since I worked on my LG UltraFine 4k recently I am not certain when it started since with the 4k Display the MBP is always running the AMD GPU. I can certainly say it started BEFORE updating to 10.12.3!
Workaround for the time beeing: In Energy saving options, disable GPU switching. This will higher the power consumption though.
If I try to search for the issue I find more hackintosch related posts - these Guys had the Issue with the same graphic card for at least one year as it looks like, and its always a problem with the driver. Makes me hope it is as well, but I will see a genius bar next week if I dont find a solution...