Several of the Plants vs Zombies 2 android achievements I already completed, e.g. complete Ancient Egypt, before the achievements in google play were introduced. Not only don't I have credit for those achievements, I can't complete them either. E.g. I just re-beat the last stage of Ancient Egypt, and still no achievement. Any ideas?
Edit: The only relevant source I can find with google would be the 1st comment here, which is not super encouraging: http://plantsvszombies.wikia.com/wiki/Achievements_%28Plants_vs._Zombies_2:_It%27s_About_Time%29
Best Answer
Assuming you've already beaten all the levels before the upgrade, you only need to complete the level before the last level in order to activate the achievement.