TricideNeo worked amazingly for my chickens!. I had four chickens with bumblefoot and nothing else was working so I decided to give it a try. I soaked their feet for 5 minutes a day for a week in the tricideneo, I didn't wrap their feet or cut into the foot. That was about a month ago and they all healed beautifully. In my opinion it's worth a try. It's utterly painless and non-invasive. here is the link to the article I read- https://ouroneacrefarm.com/2013/11/09/bumblefoot-treatment-tricideneo/
Of course this is about treating chickens but I'm hoping it would work on ducks as well. Best of luck with your duck!