It's easy to get Fire TV to respond but not the Tivo 4k. When I disabled CEC in the TV then 4k no longer responded to my old Vizio TV remote.
To test, I used Harmony to put left/ right codes for a Panasonic TV into a Flirc and the 4K did not respond. I then tried the same thing for a Samsung TV and the 4k did not respond to that either. 4k also does not respond to the Flirc Media Player of the Harmony but Fire TV does. I don't know what to try that might work for the Tivo Streamer 4k. Apparently the 4k was responding to the the CEC and since turning that off nothing else worked.
"All devices have built in harmony codes, meaning you don't have to do any pairing. So naturally, if you setup your harmony and flirc - firetv on one, the other will respond. To remedy this, open up my software, go to file->advanced and disable the built in profile on the one you don't want to respond."
You're saying to set up one Flirc with built in Firetv and another flirc with a different built in profile? And disable another built in profle which I woud teach by hand? I don't understand.