Running Windows 10 Home. HP-590. Intel Core I5-8400 with UHD 630 graphics. 2nd monitor on HDMI interface. Have the latest Intel driver and HP BIOS.
When PC goes to sleep, second monitor gives me a no signal message. Have turn monitor off and back on before it is recognized. Not the monitor. Works fine if I attach it to my laptops using HDMI, DVI or VGA. Tried all kinds of settings and cables but will not wake up on the desktop.
Have you tried the latest version of the Intel UHD Graphics driver? It is available here: https://downloadcenter.intel.com/download/27988/Intel-Graphics-Driver-for-Windows-10?product=126790 Download Intel® Graphics Driver for Windows® 10.
Hope this helps,
Have you looked to see if there is any updated firmware for the LSPcon IC? [This is the chip that converts the DP output of the processor into HDMI]
Did a web search and checked their site. Couldn't find anything that seemed to apply but don't really know which specific chip is used. They don't have an easy to use support link. I can't believe no one else has this problem.