I assume the Small business security subscription uses the consumer version try disabling access protection and update there is a a fix available but I feel it needs a reinstall or disabling AP to get it. AP is found in navigation General Settings and Alerts and Access Protection. Ensure after the update you reenable AP.
That is my initial thought if no help best you contact support
Make sure any previous security software is uninstalled and use their tool if applicable.
Completely uninstall via Control Panel > Programs and Features, reboot.
Run the MCPR cleanup tool and reboot.
Reinstall from your online account.
Thank you Ex_Brit for the pointer to the clean up tool. Uninstalling and then cleaning up and re-installing solved my problem. All good now. Thanks!
Glad it helped, good luck ;-)