Software glitch
I finished my return, but did not file. Today I discovered a 1099-Div that had not been included, so I updated the return. The new 1099-Div included $762 of dividends, so I expected my tax refund to decrease. However, it stayed exactly the same. When I look at my list of 1099s, the new one is included. I think there must be a software problem since I can't think of any other reason that my income can be increased without increasing the tax liability.