I’ve emailed NAIM about this also, just to hopefully try and push the matter. Nearly blew the speakers off my MUSO discovering this fault 
…after paying for my lifetime subscription I may add which has me debating it keeping it beyond the 30 days as I own three Muso’s.
I do feel though, after speaking to one of their engineers on the phone, they have little interest or motivation in fixing the issue as their new units are now out. They won’t even be making the old ones Roon Ready, when he admitted that it wouldnt be massively difficult to implement.