TCL 65" 6 Series Problem

I have just started having a problem where when a PS4 is plugged in at the same time as another device, in this case a NVIDA shield into HDMI's 1 & 3 respectively, and I turn the PS4 on the video and audio starts cutting out like a bad cable or something on HDMI 1 (PS4) and HDMI 3 (Shield) flickers really bad. You can't even see the PS4's input as it flashes in and out. I have replaced cables, factory reset TV, swapped HDMI inputs etc. Only HDMI 1 & 3 are affected. HDMI 2 is fine. If I unplug HDMI 3 before turning on the PS4 its HDMI is fine. So it is like the TV no longer can handle HDMI 1 & 3 input at the same time. Thoughts?