Thank you for your post.
Mac OS X 10.10.2 has not been released. Therefore, you probably have a pre-release version.
With that said, another customer reported the same problem with version 4 of the Beta release, but with a subsequent release (5?), the issue no longer occurred.
Until Mac OS X 10.10.2 is released, use FileMaker Pro on a supported operating system.
… and it says a lot that Apple already released beta 6 yesterday. I would recommend to use the most current version.