Hi
It appears @brain011 has given you a lot of good info. I’m not positive but it could just be your naming convention or your annunciation 
.
I have 4 TV’s each with a unique name (LG, OLED, Nano and Beam) that has nothing to with the room they’re in (i.e. living room, bedroom, den etc.). All but one is connected via HDMI-eARC. The 4th TV is actually a Sony circa 2010 with HDMI-ARC. Yeah..it was a bit ahead of it’s time.
The Sony (ironically) is connected to a Beam 2. The room name in the Sonos App is “Beam”. The connection (to the Beam 2) actually runs through a HDFury to allow play back of Dolby Atmos audio.
I can say to the Beam...”Alexa turn on Nano or LG or OLED without issue”. I can also do the reverse. I have Alexa set in the Beam (and so with the Arc’s) to give audible feedback by having the “chime” enabled.
FYI, from any of my Sonos sound bars I can command Alexa to play/pause/stop music on any Sonos device in my home including an Amp with 3rd party speakers called “Speakers”. LOL.
So, if none of what @brain011 offered resolves your issue,,,them you might review how your products are named in the Sonos app. Remember to speak clearly and succinctly when issuing commands.
Moderator edit: spam post referred to, copied below without spam link:
Fast solutions
1-Verify the microphone is turned on:
Check to see if the actual microphone switch on your voice-activated Sonos speaker is turned on.
Moreover, look at the status light above the
or the microphone
button for voice service. If the light is out, press the button to turn on the microphone or voice service once more before attempting the command.
2-Move your voice-activated Sonos device:
To ensure that Alexa can hear you, move your Sonos device away from walls, other speakers, and sources of background noise.
3-Activate the Sonos skill again:
Launch the Alexa app and select More from the bottom right menu. To disable a skill, select Skills & Games > Your Skills > Sonos. After disabling, click Activate Skill.
4-Look into your Amazon account;
One Amazon account can only be used per Sonos system. If you want to utilize Alexa in both locations and have a second Sonos system, you'll need to use a second Amazon account.
5-your music services together:
Before continuing with the advanced steps below, please link any music services that Alexa suggests before you hear a response like "link music services."
Modernized fixes:
If the aforementioned simple fixes do not cure your problem, use the instructions below for your Alexa-enabled device.
If you own Sonos speakers that support voice,
1. On your iOS or Android device, launch the Alexa app.
On the lower right corner, tap the More menu.
2. To disable a skill, select Skills & Games > Your Skills > Sonos.
3. Delete your Sonos speaker's registration with Alexa by doing as directed on the Amazon website: A device's deregistration.
4. Disable the Sonos app's voice control feature. using the
5. Choose Amazon Alexa under Voice on the Settings page, then tap Services & Voice. From the list of Sonos Products, choose the voice-activated item, then hit Uninstall Alexa.
6. Log out of all Amazon mobile apps, including the Amazon app, the Alexa app, and the mobile version of Amazon.com. By doing this, Alexa will always utilize the right Amazon account.
7. Redo the Alexa configuration using the Sonos app. When prompted, follow the instructions to log into the proper Amazon account.
8. Try giving Alexa another command after you're done.
If your Sonos speakers aren't voice-activated:
1-On your iOS or Android device, launch the Alexa app.
2-At the bottom right, select More from the menu.
3-To disable a skill, select Skills & Games > Your Skills > Sonos.
4-Delete your Sonos speaker's registration with Alexa by doing as directed on the Amazon website: A device's deregistration.
5-Return to Skills & Games > Your Skills > Sonos and tap on Enable Skill to re-enable the Sonos skill.
6-Try giving Alexa another command after you're finished.
