First off, CEC is fraught with "make it just work" frustration. It's a loose standard implemented by many competing companies, all with their own agendas. So making it do what you want is rarely as easy as expected. My advice is always the same: cut the dependency on it out of the equation and instead use macro programming on learn remotes so that you can push one button and make a sequence of things happen. In other words, you shift CEC-like goals to macros. When you get the macros right, it will work exactly as you want. Your Harmony remote may support macros already.
However, many want to keep trying to get CEC working anyway so let's try with your setup. Test variables one at a time until you find a possible solution. For example, if you think about the TIVO and AppleTV as "the same" (first link in the CEC chain) for these purposes, one is doing what you want and the other is not. So the first thing I would do, is unhook the HDMI cable from the TIVO, hook that same cable into AppleTV and then turn on AppleTV. If receiver and TV come on as it does now with Tivo in that slot, you'll likely pin this problem down to perhaps the (former) HDMI cable between AppleTV and receiver OR perhaps the input on the receiver for AppleTV.
If the AppleTV (in place of TIVO) turns on the receiver but not the TV. I would re-check my settings in AppleTV... and recheck my cabling between receiver and TV (even testing a different HDMI cable from receiver to TV: first, does TIVO "on" still work, then does "AppleTV" now work?)
How about that cabling? Are you going from smart box (TIVO and AppleTV) into Receiver and from Receiver to TV? Or do you have TIVO and AppleTV hooked to TV and then TV to Receiver? Given the problem, I'm guessing the former.
The proper "flow" would be smart boxes (TIVO and AppleTV) HDMI into Marantz, then single cable from Marantz out to TV (if you have more than one "out" (to TV) jack, look for one marked ARC.
- Tivo or AppleTV "ON" should turn on Receiver.
- Receiver "seeing" a video signal from either, should turn on TV to display that signal.
One is apparently working this way. The other is not. Be sure both are hooked up the SAME way... with the same "flow." Receivers generally have multiple HDMI "IN" jacks and only 1 or 2 HDMI "OUT" jacks. Be sure you are connected properly: smart boxes at one end of the chain, TV at the other end... no TV in the middle slot.
That Marantz has HDMI jacks as 1 cable/sat 2 DVD 3 blu ray, etc. I wonder if perhaps that DVD connection might be limited to DVD quality and AppleTV is trying to deliver well above that quality. Another experiment would be to try using HDMI 3 "blu ray" instead of HDMI 2 "DVD" from AppleTV. This is unlikely but easy enough to test too.
If you have receiver in the middle (Tivo and Apple TV at one end, Marantz in the middle, TV at other end), try swapping HDMI cables from TIVO to Marantz and AppleTV to Marantz.
- Will TIVO "ON" still work as it does now through what was the AppleTV HDMI cable?
- Does AppleTV work as you want it now using what was the TIVO cable or still the same?
Try swapping HDMI
jacks on the Marantz.
- TIVO HDMI into what was the AppleTV HDMI input work as it does now?
- Does Apple TV into what was the TIVO HDMI input work as you want it too or still only turning on the receiver but not TV?
Each time you change just one variable, you are narrowing down the possibilities.
If you happen to have ANOTHER AppleTV in the house, mix it into the test. For example, does one AppleTV do what you want but the other doesn't? If so, compare settings until you find what is not set up properly on the one not doing what you want it to do. If you don't have an extra AppleTV, maybe a friend does? Ask them to bring it over or loan it to you for some setup tests. If one "just works" the other should too. That discovery would scream "compare settings" for the one not working.
The big key to cracking CEC connections is to try to narrow it down to single variables and then test problematic variables. Right now, I suspect HDMI cable, (AppleTV) HDMI input on the Marantz or AppleTV (or maybe Marantz CEC settings for the AppleTV jack if applicable: perhaps something already default on for TIVO jack but not set for the AppleTV jack?) because TIVO "ON" is working like you want but AppleTV "ON" is not. However, my suspicion goes out the window if one of those is hooked directly to the receiver and the other directly to the TV. You are lucky to have one working right now. Use what you know is working to figure out the issue with the other. Swap cable and try. Then swap jacks and try. If TIVO keeps working in all scenarios and AppleTV is not, dig into AppleTV CEC settings because you've basically ruled out cabling and perhaps the whole receiver and receiver settings.
All that offered though, you are trying to test things that may or may not be implemented well, that may or may not adhere to a "standard", etc with no way of knowing if CEC is trying and failing or not. Thus, a learn remote with macros (your Harmony may offer both already) can let you turn OFF CEC on everything and "fake" CEC functionality with one-click (button) macro execution.