I am having the same issue. Did you figure out a solution?
There is no software setting or hardware setting(from Nvidia) to override this issue. If the monitors are OFF LMI will skim the GFX off the card- but the CARD will not render the 3D graphics or overdraw regions. Nvidia is awware of the issue (HAven't heard anything).
There are headless and pass-thorugh dongles and adaptors that simulate monitors on to resolve the issue. Crazy it is an issue without a software switch fo be flippe don the GFX hardware.
Here are the 'headless' display options on Amazon...
https://www.amazon.com/Headless-Display-Emulator-Headless-1920x1080-Generation/dp/B06XT1Z9TF
