Me too. I have 2 HDMI switches from Monoprice, and they both seem to have an issue with my Wii U, specifically, they have an issue with displaying blue colour schemes. It;s especially evident when booting up Windwaker. For example, If I were to leave it on the intro screen, the screen will start to have flickering black lines appear, which only gets worse when the camera shows ocean/sky only scenes during that segment. It's quite frustrating. None of the other consoles that are also hooked up to the Switch (XBONE, PS3) have that same problem.
Sorry, I must have missed it, but what problem did you have with your Wii U, and how did you fix it?