Yes, really. Just because a user encounters issues following a simple cumulative update does not mean there issue was actually a result of problems WITH that update, It could have a different cause. Such as not having updated their BIOS software when a recent update was issued by their computer manufacturer.
So until Microsoft Techs CONFIRM that the issue is with their update and no other we have one KNOWN issue.
Just by means of follow-up, a couple of days after posting, it became quite well documented on tech news sites that KB4552799 had issues with HP machines, and a patch was released.
I was extremely relieved when KB4552799 installed itself first time, a couple of days ago.
It's the first time since January that I've managed to install a Win10 update, and I've learned quite a few lessons in the process. Chiefly - when updates are released, give them at least a week for any issues to become apparent. For as long as Microsoft seems intent on treating end-users as beta-testers.