I have a recurring green screen when returning my PC from Sleep mode. To fix it, I have to un- and replug my monitor, a Samsung SyncMaster SA300 on an HDMI cable.
I run Windows 7 on an AMD A10, with a separate Radeon Sapphire RX 550 with 8 GB RAM for the system, and another 8 GB for the GPU.
Both Win7 and the driver are up to date - and I just noticed that my driver settings won't open since the last update.
For my DXDiag, see the attachment.
I am having the same problem
4k UHD screen (Samsung)
60 hz refresh rate
Unplugging and plugging back in hdmi cable fixes it