This problem may be a bug. i have spent too much time trying to solve it.
I inherited a master page to mycustom aspx pages but I can not see the aspx page content. (maybe my visual studio does not detect contentplace holder).
My master.aspx :
RESULT : This page inherited from Site.Master but I can not see contents

Why can I not see my content areas inherited page from master page? How would this issue be solved?
i think its because your div is hidden =)