Thank you for the post.
On my workstation Mac OS X Mountain Lion 10.8.5 iMac, I am able to replicate with FileMaker Pro 12.0v5 (Advanced).
I forwarded a report to Testing and Development for review.
The option does work in Windows so this would appear to be a Mac OS specific issue...
An entry has been made in the Known Bugs List and linked to this issue report. Please post all commments/questions/suggested corrections about that entry here or in a new thread. Please do not post such comments to the Bugs List Thread.
This bug has not been fixed on FileMaker Pro 13.