Just got the v6 box I have flat hdmi lead down the back of my wall the one I had wouldn't work I have now bought 2 different new ones and still no joy but the one the virgin guy left works no problem although it hangs along my wall like a washing rope 😳
There are several different specification of hdmi lead, not all will support 4k and/or certain functions so maybe you have an older specification lead. You can web search 'hdmi standards' and read the differences between them if you are interested.
However, the fact it's flat has nothing at all to do with it. I'm using a flat Wireworld hdmi lead and have no issues with it at all.
Yeah, most people just think an hdmi lead is an hdmi lead but as tv technology has improved over the last few years so the specs of hdmi leads have had to improve to keep up. They are backwards compatible in that a latest spec lead should work fine with an older tv but not vice versa.
I was berated on here for saying I use one of the newer HDMi leads and told that it was totally unneccessary and a waste of money. Personally I didn't mind spending a couple pounds more as the ones I have work *shrugs*.
It might well be unnecessary if what you had before worked perfectly well unlike the for the op in this case.
This issue will come to the fore in the future though as (to the best of my knowledge) only the latest spec leads are 4k ultra-hd certified (although previous versions were 4k non-ultra hd certified) so you are buying in some future proofing for your extra few pounds.
Berate me by all means, but i use Wireworld cables which aren't cheap but are built well, work and offer a better picture quality (in my opinion) than the freebie leads. You get what you pay for as with most things in life.
We have a 4k SUHD 3D TV and haven't changed the HDMI cable for years and I guarantee your picture is no better than ours on your new cables. It's totally unnecessary to buy new cables if the old ones work just because you have a new TV.