I don't know anything about Passion Flower but I know a little about clematis. I planted clematis (two types) two years ago. Last year, the one never flowered but reached the top of the trellis but had only two stems. Looked a little pathetic but it was happy and green. The other one last year only grew up two feet and only had three blooms...pathetic but the blooms were pretty. So I was anxious to see this years "display". The first one I mentioned has one bloom this year and the other has actually grown up the trellis unlike last year. I honestly think clematis takes a few years to "mature" and maybe could use fertilizer which I don't do normally. I would just give it time. Also, make sure that the roots are shaded with another plant or something. I have a very thick layer of mulch and white stones covering mine and they are happy. They will die if their roots get too hot. So my advice would be to give it time...I hope someone can help you with your Passion Flower. Maybe same idea. My clematis have small leaves...maybe a type???

I would love to give you the passion vine that grows and comes up everywhere around the area where we had some "rich top soil" placed by a friend. It is almost as vigorous a spreader as trumpet vine is here. (Central AL Zn 7b)

As for the clematis, look at Chalk Hill clematis site. They are going out of business after the Fall season, but you might learn (as I did) that your vine needs to be pruned hard...and it won't cost you to look and learn. good luck!
Kay