It is a new bug introduced on the 11.3.1 update,
Please do not re-install your game as it risks losing your progress, there is nothing as you or any other players can do except waiting fir a fix to be delivered by PopCap.
I've gotten this before... I know one of the solutions is I try to complete all of the tasks to get the 10 gems! (it can be different for some people)
Let's say you have the "Play today's Pinata Party" or "Win an Arena Match" left & you haven't got the 10 gems (even though you completed 8 tasks). Try to complete them and see if you can collect the 10 gems (just make sure you press "CLAIM ALL" on the top of your daily quests).
Also the screen shot you posted, yes I've gotten it as well before. I just want my 10 gems!!
It did not work
I want my diamond rewards!!! I paid for them!!!!!!
