It seems like rewards disappear after a certain period.

After I leveled up the Cathedral to 18, it disappeared in just one day and I couldn't claim the reward. For the level 24 missions, the regular and paid missions were still there, but suddenly they all vanished. They're completely gone now. I used to see Time Quests that gave items pop up occasionally, but even those are gone. Ah... I've been playing the game, and it's been fun so I kept playing and even spent money, but now I'm feeling a bit annoyed because of these quests.