check your supply units. Weapons can hide there for a long time.
W3C changed the stock market to make it constant trading. They also say they are making page load times faster. I would guess that the profit calculations are now on a lower priority. Your profits from one month might not get processed until later. Another guess would be that your profit payments and corporate taxes got put on a lower priority.
In "Over yonder" on LU the graphs for total profit, total income, and income from state corp profits have peaks and valleys in the same month and they have a similar magnitude. Based on that I would think you are receiving profit payments at when the server load is low.