The challenge is finish among the Top 3 players 5 times in Domination. Well I was just in a match where I was on the winning team in 3rd place. I had the final kill. When the match was over I went to check to see if the challenge went to the next tier. It didn't. This challenge needs to be fixed.
As get2dachopperrrr tried to explain you need to be placed in the top three out of both teams, doesn't matter if your team wins or lose's you just have to be in one of the top three scorers overall, if it's not adding them if you're in the top three then you may want to contact support for help