I can confirm that the Harmony Hub will control the new Rogers Ignite set top box. In the Harmony app, setup your Ignite box as an Arris Xi6-A (the iR codes are the same as the Xi6-T). The Rogers box is very finicky for iR reception, I have my placed back and to the left of my Harmony Hub. You may have better luck using the iR blaster cable attached directly to the front of the Rogers Ignite set top box.
I am in the same situation as you and unfortunately none of the Harmony remotes will work. All Ignite remotes us the Rf signal and harmony only works with IR. To test this for yourself, hold your ignite remote with one hand over the front and turn on/off your TV and change channels. As you will see, it work and is using the RF (radio frequency) channel. Until Rogers or Harmony can find a fix for this we are all stuck with the Ignite Remotes.
I am in the same situation as you and unfortunately none of the Harmony remotes will work.
As discussed in this and other threads on the Harmony remotes, they work just fine with Ignite because Ignite can accept both IR and RF. Of course the Ignite TV box needs to be "line of sight" for Harmony remotes to work, or the hub needs to be close to the Ignite TV box. If it's not working for you, then you likely have something configured incorrectly. Do a search for "harmony" in the Ignite forum here to view additional threads.
I use the Harmony 665 (which I believe is IR) using the Rogers Xi6-A model (although I also have the Xi6-T box). All commands seem to work just fine, although I need to point the remote directly at, and below, the box location.