Inconsistent rewards from Sniffenseeking

Me again. Another oddity, I was doing Researchers Under Fire and decided to do Sniffenseeking. Much to my surprise, upon completion I was awarded with a cache of embers. The dig event was the big gyro worm you have to spawn by whacking the little worms.

When I returned to Zaralek a couple of hours later on a different character, I did the same events, first Researchers Under Fire (still rewarding a ilevel 250 green) and then a Sniffenseeking dig. This time, however, I recieved no such cache. The dig event was the bats and crystals.

What gives?

So an update, I’ve done it on several chars now, and have received items but not another cache. Perhaps I misread or imagined the cache, but got the item.

The list is as follows (class - dig site - reward):
DH - big gyro worm - 480+ item
Shaman - bats and crystals - no reward
Warrior - 4 statues & lion - 480 boots
Rogue - bats and crystals - no
Rogue dig #2 - trigger plates and elemental balls/keys - no
Druid - muddy & sticky keys - 480 ring
DH #2 - NSWE elements and big elemental - no
DH #3 - bats and crystals - 489 neck
Shaman #2 - bats and crystals - 489 neck
DK - etched key - no
Paladin - 4 statues & lion - no
Monk - 2 keepers and 4 pedestals for orbs - 489 trinket
Paladin #2 - 4 statues & lion - 480 wrist

Bit weird.