Bananaman88

That is an inherent problem with heavily-variegated leaves. The white portion has no chlorophyll (hence, it being white) so it burns easier in the sun. I have the same issue with my 'Stuttgart' canna. Plants with yellowish variegation don't seem to have this issue as much as there is at least a little chlorophyll but, in my experience, anything with white variegation will have this problem. My last Ae-Ae burned along the edges even in the shade. I've read that Epsom salts help but I'm not entirely convinced of that. Hope this helps!