OK, well let's assume I'm a professional software engineer with 30 years experience. So I'm not running with the monitor closed or the machine sleeping. I've cleaned this machine of all extraneous applications and drivers and like I said, the configuration from windows 7 to windows 10 works fine.
So now the configuration and state of the computers is identical from that working state, and now we are just switched, running KVM mode from windows 10 to windows 7.
Both laptops have 2 nvidia cards and 2 intel cards. The intel card runs during 2d operation of each laptop. On the win 7 machine, as part of this effort to fix remote operations, got a driver refresh from mid 2019, which is my latest update for the GTX770M card. However that's not a factor, because it is not running when this problem is happening (just nvidia updaters).
Today as I wrote this I tried connecting again and I can connect, but the only thing I can bring up is task manager from the lock screen -- then the win 7 machine will bring up task manager on its main screen, but I cannot get any interactivity whatsoever.
Hopefully I've provided some additional information to you just now, you never know what might trigger a sudden insight -- right?