In Storage.GetAnyLiquidChunk() there are no checks for mass so it returns the first element found.
ConduitDispenser.ConduitUpdate(float) uses that method and then checks that the mass found is greater than 0. If it is 0 it does nothing, but that 0 mass element remains in the storage.
Therefore it will only continue work once that first element receives more mass.
Have a pump doing anything at all.