Sky Q - HDMI splitter for multiple devices

Noggin - thank you so much for your help! It's the cable...I think!?

I connected a new 4K HDMI cable to the new HDMI switch and a new 4K HDMI cable from the switch to the Sky Q box and it worked perfectly. I then connected the PS3 to another port of the HDMI switch and could flip between the too seamlessly...without glitching!

However (there's always a 'however'), in an attempt to not channel the wall and as one final check, I connected the pre-existing, non-damaged channelled HDMI cable to the input of the new HDMI switcher and used one of the new cables from the Sky Q box to the switcher...and it's working fine; no glitching and hopefully no wall channeling. This seems to point to the fact that it was actually the original cable from the Sky Q box that was at fault. I wasn't here when the engineer installed so I don't know whether he just used the existing cable from the original Sky+ box. I'm sitting amongst a plethora of wires so I don't know which is which!

Regardless, it's working and I'm thrilled. As an aside, whilst the call centre operative from Sky's Tech department was ultra helpful and consulted colleagues to try and get me an answer, she ultimately led me on a merry dance telling me a HDMI splitter / switch wouldn't work.

Thank you!