for you, and for parent: make sure you turn off "EUP Compliance"/"EU Power" or "Deep Sleep Mode" options if you have them... that's another source of issues surrounding sleep/wake with monitors.
Even apart from the monitor just hanging in the sleep state... a lot of them have glitchy behavior until you hard reboot the monitor. Some monitors actually will (internally) execute a full reboot of the monitor controller board when you wake them as a result, because they can't reliably come back out of the Deep Sleep state, and that's another source of the "monitor disconnects and windows moves my icons/windows" glitches. The monitor is actually electrically unplugging itself and replugging when it wakes.
Vendors don't really care because everyone (who's in the know) turns the feature off because it's broken and causes problems.
This particular EU regulatory exercise was a failure. Or at least, EU needs to rip off the bandaid and require that it be enabled with no option to disable it, which would obviously lead to problems and poor reviews, which would eventually lead to a fix... after a couple years of glitchy monitors.
Older monitors could also get left behind forever. There was a firmware update for my somewhat buggy monitor, but Benq will only include it with new production monitors.
I do wish reviewers paid a bit more mind to the myriad of GUI/usability issues w.r.t. monitors (waking from sleep, DP disconnects, slow menus that are plagued with inconsistencies depending on the monitor's state, etc). Sometimes, if I'm lucky, a reviewer will make a side note about it in their comments section.
Even apart from the monitor just hanging in the sleep state... a lot of them have glitchy behavior until you hard reboot the monitor. Some monitors actually will (internally) execute a full reboot of the monitor controller board when you wake them as a result, because they can't reliably come back out of the Deep Sleep state, and that's another source of the "monitor disconnects and windows moves my icons/windows" glitches. The monitor is actually electrically unplugging itself and replugging when it wakes.
Vendors don't really care because everyone (who's in the know) turns the feature off because it's broken and causes problems.
This particular EU regulatory exercise was a failure. Or at least, EU needs to rip off the bandaid and require that it be enabled with no option to disable it, which would obviously lead to problems and poor reviews, which would eventually lead to a fix... after a couple years of glitchy monitors.