Thank you for the post.
I am not able to generate a Database Design Report with blank pages, so I may need you to provide more detail for me to help.
Here is what I did:
On a Windows 7 machine, running FileMaker Pro 11.0 Advanced, I opened a new database called Test. Without putting any data in the file, I selected Database Design Report from the Tools menu. I selected the HTML format and created the file. Please see the screenshot below:
How does your result differ from this?