Zombie events don't seem to grant exp properly
In all honesty, I don't think the Zombies ever really worked properly.
They dominate low lvl characters.
They are no match for high level characters.
In either case, rewards for them stink.
Hopefully you filed a /bug report ingame and a /petition as well.
Might even want to PM someone on this, but I'm not sure which Dev would be in charge of such.
If the game spit out 20 dollar bills people would complain that they weren't sequentially numbered. If they were sequentially numbered people would complain that they weren't random enough.
Black Pebble is my new hero.
During a zombie invasion team in the hollows this evening, I had a level 40 and a level 50 both report they weren't getting experience on a team with low level players. The zombies did not appear to be scaling correctly.