Just to add, the reason I'm installing KB4284867 (2018-06 Security Only Quality Update for Windows 7) is that, for about a year now, I've had issues installing the "monthly rollup" each month. So, I just manually download the "security only" update each month and install that.
That has worked fine every month up until this one in June. All other monthly updates (Office, Internet Explorer, NET Framework) worked this month still, just not the Windows security only update for June. I figured I had an issue back when the monthly rollups stopped working, but wasn't too concerned about messing with it as long as I could get security updates. Sadly now, it seems like even those won't work.