I see, thanks. Obviously it should work, but I am not sure if the 127.0.0.1 is the problem, even if Roon may have changed to displaying this after the update. The point of 127.0.0.1 is that the local/same machine is always reachable on that address, so it seems to make sense to me.
It works here for @Geoff_Coupe on his own machine with that IP: