Samsung TVs, or at least mine, were better at controlling devices connected through an AVR than other brands. Many new TVs have Universal Remote Control functionality as well but that functionality may work only for devices connected directly to the TV while Samsung TVs, at least mine, could control them through an AVR. My LG C1 is very finicky about HDMI-CEC and Universal Remote Control. As mentioned by
@-Jim- , a direct connection to the TV may be necessary here. But, the Sony receiver here supports ARC, not eARC and lossless multichannel PCM, Dolby TrueHD and DTS-HD Master Audio will not be supported over ARC from any devices connected directly to the TV.
I have also noticed multiple Android, Apple or even a single Roku device mixed with the others will make for a mess in a system using HDMI-CEC. The setup assist on my Amazon Fire Cube Gen 3 is fantastic. I'm not sure if it is featured in the Firestick. The NVIDIA SHIELD TV Pro has the best HDMI-CEC feature set when using Developer settings. It can power everything ON and OFF and will go to sleep without interfering with anything if I switch to another input source device using the other device's remote controller. Changing out any devices makes my system go mad and I've reset EVERYTHING more times than I can count. Currently, my receiver connected devices using HDMI-CEC include an Apple TV 4K, NVIDIA SHIELD TV Pro, Sony UBP-X800M2 and TiVo Roamio. All will power the TV and receiver ON when using any of their remote controllers and all but the Sony can power everything OFF.
If just one more HDMI-CEC enabled device is connected to either my TV or receiver, everything goes to s#%t. While the HDMI-CEC spec supports something like fifteen devices, different TVs and AVRs have their own limits concerning the number of a particular kind of device and the total number of all devices. There is not one standard to rule them all and it can be very difficult to get a combination of HDMI-CEC capable devices to work well together in a system.
Many Smart TVs feature the apps many want to use but aren't as fully featured or as powerful as external streamers. But, as
@Teetertotter? mentioned, it might be worth trying to use the TVs apps to see if it features the apps needed here. You might also try unplugging all devices for a bit and see if that helps at all. Good luck.