How timely. We just had to have a situation like that repaired before we sell our house: it came up at inspection. In our case the underlying plywood was buckled and needed to be nailed down first.
This is a “barn” roof, on the near-vertical panel. There’s a second-story interior wall on the other side, no easy visibility from the inside. Was the buckling visible from the outside?
It’s been awhile since I’ve stood in the caulk section of the hardware store meticulously comparing silicones, but ISTR there being roofing tar available in caulking tubes for about $7 a tube.