Roof leaks are very hard the water travels quite a distance sometimes. Good bets are anyplace with flashing or a valley
I'm guessing a ventilation pipe on the roof. There was a lot of snow this winter and I think when it got warmer, the snow moved and managed to bend the pipe, maybe creating a crack somewhere, allowing the water in and down to the first-floor ceiling.
I chased the leak for hours without finding it. I may have to pick apart some of the first-floor ceiling to see how the water travels.