Perhaps try switching off HDMI-CEC control on the attached devices that are cabled to the TV over its HDMI ports - except for the Sonos Arc of course.
 

If you find that a device does not allow the protocol to be switched off, then you could perhaps go onto insert a cec-less adapter, between the device and the TV, such as the example shown in this LINK. That will then ‘hopefully’ stop the device stealing focus away from the Arc.

I now have nothing plugged in other than the Arc and direct tv. Still have the same issue. Even after resetting the Arc

My next suggestions are to perhaps try toggling off/on the TV HDMI "CEC" control option.

Then power off the TV & Arc (not standby) for 1 full minute. Bring the TV back online first and then the Arc.

Leave the other peripherals disconnected from the TV, just for this test. 

Then see if that fixes it.

Which Vizio TV Model is it (and what is it’s firmware version)? 

Does it have an HDMI-ARC port, or eARC?

As an aside, I would suggest not (factory) resetting the Arc, at least not until you have spoken to the customer support staff - a reset really is a ‘last resort’ option, after full diagnosis. It is unlikely to fix the type of issue you are experiencing.  

Seems to be working for now, with no other HDMI inputs used other than the Arc and DirectTv.

I would perhaps next go onto adding back the peripherals, but do it one at a time and try the setup with each one, maybe for a day or so ...and see if the issue returns before moving onto adding back the next device, to perhaps try to discover which device maybe stealing focus.

If the problem returns when a particular device is connected to the TV, then either ensure its CEC control features are disabled, or perhaps add a cec-less adapter to the connection between the TV and problem device, as mentioned in my earlier post.