Yes we are using nop-templates plugins and theme Emporium which belongs to nop-templates but we dont use One Page checkout. Also I wrote that problem to Paypal Support. We need a help.
Do you use any third-party themes or plugins (especially for checkout)?
We are using nop-templates Emporium theme and some of plugins, these are : Seven Spikes Core Nop Ajax Cart Nop Anywhere Sliders Nop Cloud Zoom Nop JCarousel Nop Mega Menu Nop Quick Tabs Nop Product Ribbons Nop Quick View Nop Emporium Theme