Your reward is from no. 50 (previous page)
Happens if you have already fulfilled the first 50 quests.
51 is unavailable until you have collect enough points, in this case 130
It's not a bug, the game show your current progress. The fact that you haven't collected some prizes on earlier pages is not a reason to show you not current page . Especially if you have a button to navigate to first untaken prize (a riffle scope with a green checkmark in it).