HTTP(S) scanning nearly everything as Malware after upgrade to 17.08 MR-8

Just upgraded my HA pair from 17.06 MR-6 to 17.08 MR-8 and now I am being flooded with syslog messages about every site visited as having a virus. I have had to uncheck the "Scan HTTP" and "Decrypt & Scan HTTPS" options from all my firewall rules to stop the barrage of messages. I have tried restarting the Web Proxy, Anti-Virus, and IPS services on the firewall, but that did not help any.

Any suggestions or am I looking at a phone call to Sophos support?