I'm running Livesafe 18.104.22.168 (4113) on an iMac still with El Capitain (10.11.6) and my updates don't work either.
According to the system log my AntiMalwareUpdate process fails with and EXC_GUARD exception. According to stackoverflow, Apple introduced this exception in 10.9 to capture file descriptor problems: https://stackoverflow.com/questions/32429431/exc-guard-exception, so I'd be interested if any Mac users can get this process to work.
Incidentally I also have a mac air running Sierra, but I had to de-install McAfee from that as it constantly ate 95% of the CPU and the battery.
So just deleted and reinstalled from logged in page on website tried to update 4 times and still recieving the message and now on the 5th time the update service has just hung!
I also run on PC and dont seem to be having an issue please resolve asap.
It seems the update issue is till a "feature" of your product! Is someone in product developement addressing it or are your sunsetting support for antivirus on Mac?