It might be worth noting that updates subsequent to 1803 are causing problems too. The same problems, as far as I can see. At least very similar, and actually worsening the situation.
Twice now I have uninstalled recent updates, KB4100403 and then KB4287903, which did seem to resolve the problems in both cases. If only temporarily in one of them. And then, when they reinstall themselves a short time later there is no problem.
Go figure.
I don't know whether this is a different issue, or whether it's a symptom of the something more widespread than app hangs alone.
Windows failing to display text properly, in a variety of situations. Failing to display icons and thumbnails at times as well.
I don't know for sure, but, when this sort of thing happens, it looks to me like it has loaded the wrong font for some of my desktop icons.