As on date Dec 2023 this is still a problem. It happens to me on EVERY flight above 20 mins on the A320. I purchased and downloaded a third party A321 and still had the problem.
Things i have tried meanwhile - APU is running. Fuel - All tanks have adequate fuel. Turn fuel xfeed on. It blanks out mostly on decent / approach or even after touchdown sometimes.
Strange is that the engines will be running when avionics blacks out but has no thrust. Screens blanks all switches non functional.
Any new / fix ideas ?