I had this same problem with blank control screens and wondered if this was something to do with the avionics master switch. Looked up the keyboard activation for toggling ‘avionics master’ which is ‘page up’ on the keyboard and momentarily turned on the screens but as soon as I released the page up button avionics screens turned off…
My solution: I have a spare toggle button on my VRinsight switch panel but I presume any keypad or button would do and I programmed that to turn the master avionics switch and it worked.
Note: I had the same problem with the new Halo Pelican and this also is working now.
Hope this helps anyone with the same dilemma!