Have you tried toggling ‘off/on/off’ the status LED in the Ports rooms settings in ‘Settings/System/yPort room name]’ in the Sonos App?

Yes. The port isn't assigned to a room, but it's in the same room with my Arc/sub/Ones.  I tried toggling the status light for each room. Status on all other Sonos components  turned off as expected. No impact on the Port. 

Sorry, I can’t parse that. The Port must be a ‘room’ in the Sonos software before you can toggle its settings. Whether it is ‘physically’ in the same room as the Arc/Sub/and One’s, which would be the ‘home theater room’ in the Sonos software. If the Port isn’t defined as a ‘room’, you can’t toggle its settings. 

It’s not possible to place the Port in the same Sonos room as the Arc/Sub/Ones… you must be mistaken. A Sonos Port has its own room in the Sonos App System.

edit: @Airgetlam beat me to it - anyhow the Port will have its own ‘room’ settings in the Sonos App.

@Airgetlam @Ken_Griffiths - I understand the port is it's own “room” and my setup screen looks the same as the photo you posted. Nonetheless, the Port isn't responding to any toggle to turn off the status light. It doesn't sound like this is a known or common issue. I've considered a factory reset but wanted to explore other options first. The port is on a shelf just below the Arc. The soundbar light doesn't bother me ( and responds if I choose to turn it off), but the Port light is larger and brighter.   

Until it shows up as a ‘room’ in your controller, it can’t be ‘addressed’ in any way, and consequently you won’t be able to toggle any of the settings. 

You can only switch off the Status LED on any Sonos product via the Sonos App room settings or possibly using a 3rd Party App (perhaps?), whilst it’s powered on and visible in the App - there’s no other way to toggle it off - I’ve just checked the Sonos Port here and its Status LED toggles off/on with no issue via the S2 App, so it’s likely a localised issue in your case.

If you cannot solve it however, then it maybe best to submit a Sonos system diagnostic report from within the Sonos App and either note/post it’s reference back here and then contact/chat with Sonos Support Staff via this LINK  and see what the Staff can perhaps suggest to resolve the matter.

@Airgetlam 

Here's my setup 

And have you tried toggling the Ports status light switch on-off and then on-off again and then leaving it off?

You could power down PORT, then force close the controller. On restart does the status light respond?

RESOLVED 

The status light now responds to the on/off toggle, but it took multitude of steps.

1. Unplug power and input RCA (ZEN phono stage)
2. Factory reset per Sonos instructions. The Port status was still flashing after 30 min, so I repeated the reset.
3. Reconnected everything once the Port stabilized.  Status light still would not toggle off. 
4. With a record playing on the turntable I cycled through the delay and source level settings. 
5. The status light now toggles on/off normally. 

Fascinating. I can see no reason why a factory reset would have made a difference, other than reload the OS completely.

At least you’ve resolved it. 

Yes, that’s really quite strange behaviour, I would maybe just keep a lookout for the Port, going forward, but glad you got it resolved for now @MrZack.