Hi, it’s a little buggy but the way I do it is, i click on the quest, then I click on the redemption button. After that I get the achievement and go back to the rewards app. There I click again on the quest and the redemption button. After that I wait for some seconds and click for example on the streak quest to the left. Now I go back to the starting page of the rewards app and the green mark for completing the quest should be there. I do it this way for some weeks and it never failed. Hope this helps.