For More Information see: Sometimes global field in header become disabled
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html
Thank you for your post.
As you can see from the link provided by PhilModJunk (Thank you), our Development and Software Quality Assurance (Testing) departments are aware of this issue.
I have attached your post to the original reported case.