Just another data point.
Prior to 4/15 my Pro 4 would routinely crash if left sleeping overnight. I was routinely using Hibernate instead of Sleep.
After installing the Watchdog timer update and the 4/15 Intel driver updates my Pro 4 miraculously became a reliable sleeper. I was about to post this when the 4/19 updates arrived and installed without problem.
Wakeup from sleep was still good but some bugs appeared. The most serious was that if WiFi was not enabled during sleep the service would not restart at awaken. It was necessary to restart the OS to get the service back. The work around is not to sleep WiFi.
Other observations, although I cannot be certain when these appeared.
It is no longer possible to add Sleep and Hibernate to the Start menu Power item.
Although password is set to not be required after Sleep and Hibernation, Hello still comes up after sleep. It does not come up after Hibernation
I use a U-blox7 USB GPS receiver to navigate maps (Highly recommended BTW - $14 on EBay. Installs in a snap. Very sensitive and accurate. ) It has an LED showing signal acquisition, It does not power off during sleep. It does power off during Hibernation.
A USB mouse is turned off during sleep. Maybe this behavior for the U-Blox is by design.
The display driver has gone backwards in its ability to show minor roads clearly in Maps. The gamma setting for the display is set correctly. Maybe this is really a Map app problem as visibility of minor roads is not all that good on other displays.
I hope someone in MS is monitoring for these kind of reports.