thurrott[.]com/windows/windows-10/107646/microsoft-updates-shipping-versions-windows-10-third-time-month
As I surmised earlier, I’m going to guess that this sudden explosion of cumulative updates is somehow tied to the pending release of the Windows 10 Creators Update, which is a major OS upgrade. The timing is just too obvious.
I tend to agree, but I'm also going to go one further and suggest recent optional updates for 7/8 *might* be doing the same thing. Remember, with the Creators Update Microsoft's changing how updates are delivered across the board -- maybe problems switching over at their end was responsible for no update Tuesday in February.
Anyway, reason I'm mentioning it is KB4015438 giving me problems in 10... after installing it there was quite a bit of network-related stuff going on in 10 when I was watching Task Mgr. And despite 3 tries it wouldn't install to my tablet -- that wouldn't have happened if there wasn't something fairly major happening [I dread the same sort of network-related problems that kept the tablet on the shelf for 1.5 months with the version of 10 before last].
So be extra careful about updates for the next few weeks, regardless the version of Windows you're running.