EDIT: Ha ha, Verdite beat me to it! I'll still post this, but it's pretty much the same as what Verdite says above
As a workaround, you could set the auto-gold drop to 0 and make a normal "gold coin" item which the enemy drops when defeated. You then make an "always on" event that checks if the player has the 'gold coin' item. If they do, the event is triggered and removes the coin item and increases the players gold. If you set the gold coin item to 'non-crucial' the old drops should be culled out if they don't get picked up.
The event would look something like this
Event1 - Always On (Start condition: Have Item "Gold Coin" quantity > 0)
Change Player Parameter (Item# "gold coin' decrease by 1)
Set Player Parameter in Counter (Have Gold Amount in Counter#1)
Generate Random Counter Value (Counter#2: Between 1 and 100)
Change Counter's Value (Counter#1 Increase by Counter#2
Change Player Parameter (Amount of Gold Set to Counter#1)
Display Message "Gold Obtained"