Applied lens blur refinement brushes darken when viewed in LR mobile

I used Lens Blur on a picture using LR on PC desktop, the result displayed fine on LR mobile on iPAD. 
I applied a Lens Blur refinement focus brush on PC ( not available on LR mobile ) that worked OK on the rear dog on PC, but when synced to LR mobile the brushing over the dog showed as a shadow as well as focus refinement. See before / after screenshot looking at rear dog.