I have an issue where my external monitor (ViewSonic) will not wake up. Why I think it's related to Fedora is the following:
Fedora recognizes the monitor's existence when I go into settings. However, the monitor will not turn on. I have tried xrandr with no luck. I have also tried Alt + F2 -> r with no luck. I have a docking station, but have also tried plugging the monitor directly into the computer. At first I thought it was related to plugging the monitor in before waking from sleep, but I just plugged it in while the machine was awake with the same experience. I would say this happens once every few days with no real pattern.
Machine info:
Lenovo T470s
Fedora 30
Gnome: 3.32.0
Which kernel is showing the problem, 5.2.x ot 5.1.y or both?
In case you are running 5.2 version, can you try installing and/or booting with kernel 5.1.20-300.fc30.x86_64 and see if it works?
In case then 5.1 works it can be related with the bugzilla I have opened
https://bugzilla.redhat.com/show_bug.cgi?id=1744905and you can add your info there.