Passiflora Amethyst Yellow patches on leaves

Hi all

Please can anyone help identify what may be causing yellow spots / blotches / patches on my Passiflora Amethyst (Lavender Lady). New growth is fine but the older lower level leaves have developed the yellow patches. I have sprayed with copper based fungicide (Copper Residue of which is still visible on leaves).

Is it Heat / Sun burn... it is facing south and also gets a little windy too. Only the older leaves are effected so maybe it is the strong sun just after our patchy rain that's burning the leaves?
Is it Mosaic?
Is it Chlorosis?... Looks a little too patchy and erratic for Chlorosis.

Pictures are below.




Hope someone can help