Mysterious case of slow increase of ICP in neuron

I am using neuron 8531975871475568841 to submit manage proposals (5 per day) to cause other neurons to automatically merge maturity. Naturally I expect to pay a small fee for the creating these management proposals per proposal.

However afterwards, when I inspect the neuron, it slowly begins to increase the ICP stake after the management proposals are submitted and executed. Any idea into why this would be the case?

Screenshots attached