Built-in Alexa in Q800F soundbar works, but only about 10% of the time

Earlier this week I bought a new TV and soundbar, both from Samsung. The soundbar, Q800F, has Alexa capabilities built right in. When I say Alexa, 5% of the time it works perfectly, I make a request and it actions something, such as turning on a lamp.

The other 95% when I say ‘Alexa’, the soundbar lights up and makes a sound, but the lights immediately go off again as if the message has ended. I’ve tried resetting the soundbar and removing/relinking with Alexa app/SmartThings app, twice. It’s not a wifi issue as the router is almost directly next to the soundbar, and in the SmartThings app it says it has full bars of connection to my router.

My other thought is that another Alexa could be hearing me and cutting this one off, but there are none other in the room, and it still happens if I turn off all Alexas in the house.

In the UK in case that makes a difference.

Anyone have any ideas?