When we got married, we had a very very small wedding. We didn’t want to invite any of the aunts and uncles on my MILs side of the family because it seemed like a gift grab. They lived 3000 miles away and I had never met any of them. My MIL insisted…and we invited them…none came. All sent gifts.
In the case of the OP, none of the aunts and uncles were invited. Yes, disappointed. But consistent. I’d work on that long term relationship with the niece, and not the one day event.