Here is my setup:

• TV: TCL 65" Class 4-Series 4K UHD HDR Smart Android TV – 65S434
• Devices: Apple TV HD (A1625) (I will try an Apple TV 4K and an HDMI 2.0 cable as well to see if that solves that, but I haven't purchased those yet)
• HDMI Cable: AmazonBasics High-Speed HDMI Cable with Ethernet (should be an HDMI 1.4 cable)
• TCL Settings: Enabled T-Link and all toggles in the TV menu (Auto Power On, Auto Standby)
• Apple TV Settings: Control TV's and Receivers turned on ( https://support.apple.com/en-us/HT205225 )

My current behavior is the Apple TV can turn on the TV and it will set the input correctly, so the Apple TV will display. However, I cannot turn off the TV when I turn off the Apple TV from the Apple TV menu (Sleep now / Sleep All Connected Devices). With a different TV (Insignia 32" HDTV) the Apple TV can turn off and on the TV properly with no issues, so I doubt the cable or Apple TV is a problem, it just seems like the issue is on the TCL.

Has anyone else experienced this problem?

I've done some investigating and since the TV is an Android TV, you can enable Developer Options and you can connect the adb to view logs to see if anything abnormal is happening when the Apple TV is performing the turn off all connected devices. Here is the log output when "sleeping" the Apple TV and connected devices. Basically it seems like the HDMI CEC implementation is not working.

11-23 17:12:28.558   628   628 D HdmiCecLocalDeviceTv: ---dispatchaMessage--fuli-
11-23 17:12:28.558   628   628 D HdmiCecLocalDevice: ---onMessage--fuli---messageOpcode:157
11-23 17:12:28.659   628   628 W HDMI    : [1]:Unexpected broadcast message: <Report Power Status> src: 4, dst: 15, params: 01
11-23 17:12:29.813   628   628 D HdmiCecLocalDeviceTv: ---dispatchaMessage--fuli-
11-23 17:12:29.814   628   628 D HdmiCecLocalDevice: ---onMessage--fuli---messageOpcode:144
11-23 17:12:29.814   628   628 D HdmiCecLocalDevice: --onMessage--fuli--
11-23 17:12:33.900   628   774 W HDMI    : [2]:Failed to send a polling message(0->1) with return code -1
11-23 17:12:34.080   628   628 D HdmiCecLocalDeviceTv: ---dispatchaMessage--fuli-
11-23 17:12:34.080   628   628 D HdmiCecLocalDevice: ---onMessage--fuli---messageOpcode:144
11-23 17:12:34.080   628   628 D HdmiCecLocalDevice: --onMessage--fuli--
11-23 17:12:34.135   628   774 W HDMI    : [2]:Failed to send a polling message(0->2) with return code -1
11-23 17:12:34.216   628   774 W HDMI    : [2]:Failed to send a polling message(0->3) with return code -1
11-23 17:12:34.342   628   774 W HDMI    : [2]:Failed to send a polling message(0->5) with return code -1
11-23 17:12:34.423   628   774 W HDMI    : [2]:Failed to send a polling message(0->6) with return code -1
11-23 17:12:34.504   628   774 W HDMI    : [2]:Failed to send a polling message(0->7) with return code -1
11-23 17:12:39.000   628   628 D HdmiCecLocalDeviceTv: ---dispatchaMessage--fuli-
11-23 17:12:39.001   628   628 D HdmiCecLocalDevice: ---onMessage--fuli---messageOpcode:144
11-23 17:12:39.001   628   628 D HdmiCecLocalDevice: --onMessage--fuli--

UPDATE 1:

I called TCL Support and told them about this issue, but they didn't have a solution. I installed cec-client on a Raspberry Pi and I was able to verify that the Apple TV is definitely sending the correct standby broadcast message. But again the TCL is just failing to handle that broadcast message. I am not sure if this a common problem with other Android TVs, but it appears that Android TV OS has the correct HDMI classes , but my guess it's also up to the TV manufacturer to implement and respect the HDMI-CEC messages.

I created a solution using a Raspberry Pi which will listen for the broadcast message using HDMI-CEC and send a standby command using adb (Android Debug Bridge). If you're interested in using it, please go to https://github.com/paulsaccount/hdmi_cec_to_adb . Setup instructions on the README.md document.