I got tired of waiting and uninstalled Avast on my primary/desktop PC. (I'd been needing to do that anyway to get rid of a scheduled Quick Scan which, since Avast removed the Quick Scan feature, I could neither modify nor remove...SIGH. A+ work, Avast.) Upon reboot, WU immediately found & downloaded the update. It's now installed and my PC is still functioning normally.
My laptop, which still has Avast installed, still cannot find the update. I'll probably do the same removal/update dance on it when I have the time and energy. Or wait until Patch Tuesday and see what happens then.
I'm still debating reinstalling Avast on the desktop. This issue + unwanted feature creep + the Quick Scan issue have turned me off Avast a bit, tbh.
I did the uninstall / install Microsoft update dance as well on my Windows 10 laptop.
After the update (but before reinstalling Avast!), I ran a quick and dirty benchmark. I didn't see much if any change in performance. I suspect that if I stress test MySQL on the laptop I'll lose about 10% performance. Since it's a development machine, I'm not too concerned at this point.
I reinstalled Avast! after the benchmark, and then rebooted the system. I haven't experienced any issues as of yet, but I've not stressed the environment. I have MySQL and Apache HTTPD running on the machine, so I'll do some development work, start up Tomcat (a Java servlet container), and then test. I don't anticipate any issues.
I will wait for patch Tuesday for my desktop systems since they're both running Windows 7. If the updates don't happen then, I'll do the Avast! uninstall and re-install dance for them as well.
Hopefully Avast! and Microsoft will have a conversation to get this straightened out soon. I don't want to uninstall and re-install Avast! for every major Windows 7 / 10 update.
TL;DR version:
1. Uninstall Avast! / reboot
2. Install Microsoft updates / reboot
3. Benchmark
4. Install Avast! / reboot
5. (knock on wood - no issues yet)