I had a similar issue on my MWG running 18.104.22.168. I spoke with support and when they looked at the files that failed to scan they indicated the issue would be fixed with a GAM engine update being released this week. My current engine is showing as 7001.1402.1908 and I was told it should be fixed on 7001.1403.1970, which should be already available on some later builds of the MWG.
Ah, I see. I'll check my versioning when I get into the office tomorrow and report back.
So, my appliances are now running 7001.1403.1970 and the issue remains. I may look to raise a TAC case too.