I stumbled againts the same brick wall as you, while I was doing all the testing to update the original "HowTo" message. The problem is that "there is no problem"... Well, sort of, to say it simply: Gnomad2 does not support ogg metadata, plain and simple. I've already submitted a feature request (as per Linus's own suggestion [Linus Walleij, not Torvalds, of course!]), maybe you could submit or add to that too, so it will get implemented faster? Have a look
here