Appears Apple did not care to wait and fix this problem with external monitors (4 or 5K) Its definitely present in the release 11.0.1 and makes Apple look like Microsoft when it comes to software quality. This was not a problem prior to the upgrade on launch day, but present after first wake from sleep. Running on Mac mini 2018, which "kind of" depends on an external monitor - after sleep the monitor keeps turning off and on whenever you click on anything, anywhere on the screen. Only solution I've found so far is change resolution to anything and back again. Which solves it until the next sleep/wake. I'm an Apple fan, but also getting very annoyed at the software quality level they are releasing on their customers these days. Have had many problems with the last couple of MacOS versions and this new one is no different.