Thank you for posting you solution. Helped me fix my current problem.
Hello, I have faced the same problem and found the bug. Problem is that php empty($mixed) function returns true in case $mixed = 0.
Since I prefer not to modify the core, I have extended grocery crud as described in this thread http://www.grocerycr...ample-included/
after that it is enough to override getStateInfo method in this way:
apart from it I found and workaround other problems in search function described here http://www.grocerycr...ies/#entry14231