Missing rewards for completed quests

It pisses me the hell off because sometimes, when I complete my daily quests, I complete 8 or more. One of the daily quests is to complete 8 daily activities for 10 gems. But sometimes, when I complete 8, and I try to claim those 10 gems, it won't give me. I even try to complete more quests, such as 9 or 10 but it still won't give me that 10.😡