I doubt this is specific to new grounds. It must be the way they handle iframes and other websites doing it will also have problems. I thought I read somewhere this was resolved. Changing runtimes to and older/newer one might help that came before/after the breakage. But I'm not sure if you are experiencing the same issue I read about and really the HTML5 export is so broken I never really used it ever since I purchased it (I was hoping for better when I bought it thinking they may have gotten their sh*t together after getting help with YellowAfterlife with all those bugs but apperently it didn't take long for it to go back to being broken again).