"Old" pooled treasure disappearing upon new treasure entering pool

During a dynamis run in Buburimu today along with a friend in a party, we noticed that our drops were low. I then checked the treasure pool before and after acquiring 4 t.shells in the pool. Those 4 t.shells displaced 4 o.pieces in the pooled treasure, which mysteriously vanished - None of the o.pieces were awarded to anyone in the party. We checked it again after acquiring another few pieces of currency, and again some items got displaced and were not distributed amongst the party.

Did anyone in the party have a full inventory?

Are you going by log messages or are you actually checking you inventory after they "disappeared?" The log lags a bit with respect to the treasure pool and some messages can be dropped entirely, but that doesn't necessarily mean the items are gone.

Standard behavior is that items forced out of the treasure pool like that are distributed immediately.

Neither of us had full inventories, and I specifically checked the treasure pool before and after new treasure was introduced.