What do you mean by dropping out? Intermittent then returning?

What audio is dropping out? Is it audio from TV broadcasts, or from (say) an Apple TV box or set-top box etc? 

Do you have the Beam connected to the TV’s HDMI eARC port? Is it the HDMI cable that came with the Beam? 

Yes on TV

my own hdmi but good quality lead

need to check the port as didn’t realise there are different hdmi ports!