I am having this exact SAME problem. I have php 7, downloaded php 7 version, followed all instructions and am left with a blank screen like his. PLEASE HELP!!!!!
Under products that have attributes and variations, I cannot have more than 4 size attributes show up (only M, L, XL, and XXL); I have XS and S too under products->attributes, but they don't show up. Plugin also freezes on the plane loading screen when making picture changes or importing reviews.