Got it .. just tried it out myself with ln.tips. They are storing the comment outside of the invoice itself. So, we’re both right :D. You can’t set a comment in the bolt11 invoice when doing NIP-57, but it is possible to create some out of band way of making the comment visible to the recipient. I’ll have to sit on that and think about how to implement in Bitcoin Jungle wallet…we don’t have any mechanism to fit that into today.