its something with that monitor , mine did the exact same thing , only monitor to ever give me this issue ive tried 8 different configurations on this pc .
the nice part is there is an easy way around this . plug both the dp cable and dvi d in the monitor and boot pc , for whatever reason the pc sees two separate monitors , switch to the dp connection " shown as monitor two windows " turn the monitor input over to dp . this might take a couple tries but once the monitor shows a signal like it should all you have to do is shut down pc and disconnect the dvi dl cable and boot pc . it now will see the dp connection to the asus monitor and work from there on out , everyone who has this monitor has had this issue .
I think i've found a solution to our problem. I was struggling for 2 months with this HDMI output. I thought it was a problem between both the integrated graphics and the AMD graphics card. After shutting of the integrated one in BIOS, I still had those problems. Sometimes it works, many times not.
When my screen was black again after the PC came out of sleep-mode, I pressed ALT-F4. AMD HDMI OUTPUT just worked again. But then i saw that my "speaker-icon" was disabled (big red cross). Clicking on it opened windows 10 troubleshooter, and fixed it.
Now, for your fix (which seems to work for me for 2 days now): right click the "speaker-icon" in the desktop tray -> select "playback-devices" -> right click on any of those devices and make sure "show disabled devices" and "show disconnected devices" is turned on -> disable all disconnected (unused) "AMD high definition audio devices". Should be about 5
I hope it works out for you!