PvZ 2 crashes after each level

Hi! My problem would be that Plants Vs. Zombies 2 constantly crashes when finishing any level with a reward (new plant, costume, etc.). I've had the same problem before - I reinstalled the game (and lost my complete progress, but that's not the biggest problem), and it seemed like the problem was solved. But today I updated the game to the Dark Ages stuff, and it's the same again... When finishing a level the game crashes without granting me the new plant, perk or costume which I'd normally get. After I open it again, the level is already completed, but I don't have the reward... It's pretty annoying. And yes, I've already tried the steps mentioned in "[FAQ] Troubleshooting for iOS Games", it didn't help. Thank you in advance for your help!