Screen stays black when computer "wakes up"(Win10 install on ext ssd)

[mike_gt2]

Hi all! I have a 2014 5k IMac and installed windows on an external hard disk. It has been flawless except for one thing. Has anyone run into an issue where if you go away for a while, when you come back you can see the imac is in sleep mode but the screen still stays black when you move your mouse or touch a key on your keyboard? I even disabled sleep and left turn off screen at 5 minutes. to my surprise it still did it. when i force shutdown and power back up and load win10, once im in a get a message in blue saying to leave usb plugged in. What is going on here?

I am running Mojave on my machine.
iMac with Retina 5K display, macOS 10.14

 

[mike_gt2]

Anyone?

 

[mike_gt2]

i also found several Event id 41 instances: The system firmware has changed the processor's memory type range registers (MTRRs) across a sleep state transition (S4). This can result in reduced resume performance.