What kind of crap is this?
I clicked the link in the OP for KB4103721 and found it was available from MS Update Catalogue. Never offered to me as an automatic update, afaik.
Even then, trying to install it gives me some unknown error. Please note, as well, the lack of or corruption of fonts in text fields.
I've seen it before, since 1803, but not as bad as the example above. Restart seemed to fix that, so the message seems to be:
It's NOT already installed! Not as far as I can see anyway.
I uninstalled KB4100403, because it didn't seem to apply to me and seemed to make matters worse.
Still I'm stuck with a below par system, thanks to 1803.
Is anyone actually monitoring this thread any more?