Before @Lurker_Returns posted a response, I was going to reply with something (unhelpful) like, "yes, unless you can find an intermediate device that can down-convert the 4K content to HD, that is compatible with the set-top box and with the TV." If somebody can recommend such a device that works for them, great.
I also know that the 4K output on the Ignite set-top boxes can be very finnicky. On one 4K TV that I set up, the STB would not work on all HDMI ports, even though they could all accept UHD inputs. Others have reported problems with HDMI handshakes (HDCP errors) when going through an AV receiver.
On a more practical note, apart from some Stingray 4K channels, all of the other 4K channels on Ignite have HD counterparts, that you would be better off using anyway with an HD TV.
"Isn't there an add on to the ignite box that gives you a work around for this?"
Is there a specific reason you want to do this?
You're not missing any programming - the 4k channels are literally just mirrors of their HD equivalent, albeit in higher resolution.
Didn't I just say that? 🙂
When I was a Fibe TV customer, I had their 4K PVR connected to an HD TV, and it down-converted the 4K signal and allowed me to watch 4K channels on my HD TV. With Fibe TV, the HD channels were 720p, highly compressed and sent at a low bit rate... low-enough quality so that you could run 3 simultaneous HD streams AND home Internet over a two 15Mb/s pair-bonded VDSL links. Watching a 4K channel allowed you to watch the broadcast at 1080p quality. However, this is not necessary with Ignite TV; the HD channels are good enough and there would not really be any benefit to down-converting a 4K channel.
How do I find list of 4K channels on Ignite TV? Are there any 4K channels available apart from some sports channels?
Rogers has grouped all the 4K channels in the Guide starting at channel 970. (There are currently only a handful of 4K channels available)
You can also find 4K movies by clicking the Rogers (Menu) button, then going to "On Demand / Movies", then scrolling down to find "Movies in 4K"