product size disappeared

hi! i use this plugin to send xml feed to skroutz. Everything was fine since today… Skroutz sent me that half of my products doesn’t have sizes. I checked my site where everything was good. I can see sizes and i want to point out that xml feed refreshes every hour and i have up to a week to make changes on products. I also tried to add a new product and still sizes doesn’t appear. Why is it happening?