Disconnect the Arc from your TV and unplug both from power for about a minute. Then plug them both back in. Turn on Anynet+ on your TV and redo the TV Setup process in the Sonos app. Don’t reconnect the HDMI cable from the Arc to your TV until the app instructs you to.

I found the solution on another thread here.

Simply unplug the power cord from the TV, let it sit unplugged for a few minutes, plug it back in and voila!

If anyone has more troublesome ARC HDMI-related issues, below, is my instruction to fix it.

ARC (Audio Return Channel) HDMI Install/Configuration for Home Theater System (TV, AV Receiver, Disk Player)

STEP 1 - INSTALLATION

A - Wiring:
1. Need two ARC/eARC HDMI cable
2. TV - Insert the first HDMI cable into designated, 'HDMI ARC' port. Connect this cable to the sound system's Audio-Video receiver's designated, 'HDMI ARC' port.
3. Using second HDMI ARC cable, plug into regular 'HDMI' port on the disk player and other end into the regular 'HDMI' port on the audio-video receiver.

B - Power On All (no specific order):
1. AV Receiver
2. Disk Player
3. TV

STEP 2 - CONFIGURATION

A - Configure the Samsung TV
1. Click on 'Settings' button or scroll to the 'Settings' on the screen.
2. Select 'General', then 'External Device Manager'.
3. Turn on 'Anynet+ (HDMI-CEC)'.
4. Go back to the main page of Settings, select 'Sound'.
5. Select 'Sound Output', and set it to 'TV Speaker'. Do not set it to 'Audio Out/Optical'. After the AV receiver is properly configured, 'Receiver (HDMI)' will appear on screen.

B - Configure Yamaha RX-V385 Sound System
1. Using TV remote, either click on input/source button or scroll cursor on screen to select the HDMI source that your home theater system is on. This will
allow you to view the display from the sound system's AV receiver when you press either the 'Setup' or 'Option' button on the remote control.
2. Click on 'Setup' button on the remote.
3. Select 'HDMI'.
4. Configure to have the below:
HDMI Control = On
Standby Through = Auto
4K Upscaling = Off
HDCP Version
TV Audio Input = AUDIO1
Standby Sync = Auto
ARC = On
SCENE

C - Check AV Receiver Display
1. Remote control - press the 'TV' scene button. AV Receiver displays 'AUDIO 1'.

D - Configure The Option In AV Receiver
1. Remote control - press the 'Option' button.
2. Select 'Input Select'.
3. Needs to be: Input Select = AUDIO1
4. Select 'Audio In'.
5. Needs to be: Audio In = AUDIO1

STEP 3 - TEST ALL ITEMS

A - Play videos from the smart TV's apps and play a movie disk in the disk player.
B - Play music from the sound system AV receiver's tuner/radio.

*This instruction is specific to Yamaha RX-V385 sound system and Samsung TV but can be used as example to help with other systems.