Security Update 2019-005 Incompatable with my OS X

So, the High Sierra Security Update 2019-005 showed up as an update in the App Store. It appeared to download, but would not install, nor could the file be located anywhere on my system.

Per a number of threads with similar subjects, I directly downloaded Security Update 2019-005. When I attempted to install it, I received the message that the update was incompatable with my system (but that I could install it anyway, if I desired...) Needless to say, I didn't complete the install.

Any thoughts as to what is going on with this wonky-wayward update?

TIA

Wonky-Bob