We have the same problem and I rang customer service. The person was very nice, but didn‘t seem to be aware of the problem or knew what audio description was.
A hard reset didn‘t work, so he arranged to send me a new tv-box.
My wife sorted it just now.
Go into the program, click on info. Select „Audio“.
Then you see a tick next to „Audio Description“. There is an option „English“. Select this.
if you look at the tv-guide, most programs will have „AD“ written in their box.