I have a similar looking problem on a couple of plants and have been trying to decide if it is rust (fungus), which I saw all over a tree in my yard, or a phosphorus deficiency. For me, it seems to only affect plants in mid or late flowering. As I am a recovering over-waterer, it could be that (although RH stays steady at 45-50%). I'm using FF Happy Frog, which seems to drain pretty well. Since flowering, I didn't want to spray and dipped some leaves in a garlic dip and sprayed H2O2 (hydrogen peroxide) on the soil surface, pots and surrounding grow area (tables, trays, etc.). Temps under HPS ranges 74-82 F. I took some pics, but don't know if you can tell anything from them. I'll have to get my girl to take some pics with the good cam later. Goat's pics look like what I'm seeing. Any thoughts?

Also, recently had some cuttings that had brown spots on leaves, a new thing for me. 2 other new factors that round, filtered tap water instead of distilled grocery store water and cloning in soil instead of peat pellets. The spots disappeared or discontinued on the cuttings I kept.