Thank you for your post.
The Mac machines that have FileMaker Server 11.0v4 (current version) installed are Mac OS X 10.5.8 Server and Mac OS X 10.7. In both cases, I am unable to replicate the problem when accessed by FileMaker Pro 11.0v4 clients on Windows XP, Mac OS X 10.6.8 and Mac OS X Lion 10.7.1. In all cases, I am able to find values in the "num ys" field and return the correct results.
I do not have FileMaker Server 11.0v2 to test, so please update to FileMaker Server 11.0v4. Then, verify the example you sent me as this may have existed in 11.0v2 but changed in a subsequent version.
Actually, the issue appears to be intermittent. After a server reboot, I cannot reproduce the issue either. I will continue to monitor and schedule an upgrade to 11.0v4 at some point in the future.