Coop thanks for the reply,
GPU is AMD RX 5700 XT, brand new and drivers are up to date. The PFD & MFD pop out just fine initially but if the window icon is clicked to put the pop up in a window it flickers, with or without Air Manager and without trying to move it.
When I've got a windowed pop up and I restart the flight it persists as it should but that's when I get the black background. (but its not flickering anymore)
I've got two computers running X-Plane, normally one for scenery and one running X-Plane and Air Manager. I get these same results running the SR22 on both computers.