Rules with computer object created in Visual Policy Manager/Local Policy did not match right after an upgrade to SGOS 188.8.131.52 or above.
Proxy uses Reverse DNS lookup to lookup for Computernames from IP.
However by default Reverse DNS lookup is disabled starting SGOS 184.108.40.206 or above to enhance security.
See article TECH246181 for more information.
Refer to solution in TECH246181 to turn on Reverse DNS Lookup