Yes, but it would help to know which Passiflora it is. If you don't know the name, please post a picture of the flower.

Mine was doing that too; it was the heat. As long as the temps were in the 90's to 100's, all the buds died, most often when they were barely just visible. Now that our temps have dropped into the 70's and 80's, lots of buds are growing and a few have already opened. Giving it some light shade might help, but when the temps drop, see what it does...