JB...looking at pics of Jasminum rex the flowers have more rounded petals than the ones in your pic, which I'd describe as long, slender(er), some lanceolate petals.
I wonder if you have two species of Star Jasmine and the slight difference in the leaves could be due to age or perhaps it crossed with something, eh?
Just guessing here. Especially since J. rex isn't supposed to have a fragrance.
Or did you ever come to a conclusion to this, since I now notice it was posted last month?
Shoe (a day late, dollar short) :>)