Problem using Apple TV with UR5U-8780L remote

I’m trying to consolidate my pile of remote controls down to one master remote. My DVR/cable box remote from Charter Spectrum is the most versatile one that I have, so I’m using it. Its a model UR5U-8780L, which is the same as the widely used one from Time Warner. I had previously assigned all the device buttons on the remote to my DVR/cable box (CBL), Sony (not smart) TV (TV), LG DVD player (DVD) and Denon receiver (AUX), except for the VCR button, so I was going to assign the Apple TV to it. For some reason, I couldn’t get that to work in the Learn Remote setup step (No signal received), so I tried setting it up using the DVD device button instead and that worked fine. Now the cable remote works fine for every function.... EXCEPT it won’t turn on the Apple TV box. I still need to use the Apple TV remote for that, which defeats the whole purpose of this exercise. Has anyone come across this problem and solved it, without having to buy another universal remote?