Screen does not support HDCP - HELP

[SussexWolf]

Sky Q 2TB box and new LG C4 tv. All working fine, then HDMI switching stopped working reliably, then the dreaded blue HDCP screen tonight. The tv definitely supports HDCP and has HDMI 2.1 ports. It was all working fine before, same cables. Having read this forum, rebooted the Sky box, and all working again. Clearly it's a Sky Q box issue. 

Hopefully we will be moving soon, and I will send this junk back to Sky.