Just for the sake of being thorough. I bought a Rocketfish 1x2 HDMI Splitter from Best Buy today. $80!!! lol. Well, it doesn't work properly either. It wants to, but it just doesn't. It's very temperamental. The PS4 output goes fine to the TV without the capture device being in the chain. Plug in the Elgato, and both output pictures flicker.
Oh well, I'll return this one Tuesday lol.