It took the IRS just two days to start processing $1,400 stimulus checks after President Joe Biden signed his $1.9 trillion relief package into law. The third direct payments of the pandemic began to show up in bank accounts last weekend.As of Wednesday, millions of Americans had already received more money to take care of bills, pay down debt, save or invest.But if you keep refreshing your online banking and still aren't seeing the cash, what's happened? Here are seven potential reasons you haven't gotten your money yet.Advertisement1. The IRS is sending out the stimulus checks in 'batches'The IRS has...