Ad bug that only happens with 1 particular ad

Whenever I watch the Lords Mobile ad it does not give me credit for it. I’ve watched it over 15 times on different days and it has never paid up. Sometimes it would appear 4-5 times in a row and I would watch it until I run out of ads. Every other ad works except this one. And I also don’t know why this ad keeps showing up instead of having a variety. It’s been happening the last 3 days.

I’m using iPhone 6 with the latest iOS.