I've been able to complete them by doing one of the following, note-so far I've only had this for defeat 'x specific enemies', not sure if this can work on other types of challenges:
1) Log off, log back on and defeat one of that specific enemy type. It will often instantly complete even with just the one mob and give me the bulb.
2) If 1 doesn't work, defeat at least enough of the mobs to satisfy the amount (25, 10, etc.), then log off and back on again, defeat one more mob and it's worked.
I've always been able to get these done via one of these 2 methods, but again, I've only tried this for 'Defeat 20 enemies in giddy park' or 'defeat 25 scientists', etc. If you get a stuck one like 'complete 3 PvP matches' I'm not sure if this will work.
This has to be fixed!
