Security Rejection (Dubai)

Hi everyone. I am in Sharjah and sponsored my husband for his residency visa. It got rejected due to "security" reasons.
They don't tell you the exact reason but he has a clean record and has previously worked in the GCC so not sure what has happened.
I am on a British passport he is on an Australian passport and I have successfully sponsored and got residency for my daughter.
Really stuck as to how to proceed now. My work HR and PRO are no help so whatever you suggest I do it has to be something I can do on my own