Hi Dravin,
Sorry you're still not having luck. I am no expert in this but the only thing that seems to be fixing this for me is a Windows Restore. Did you try a Windows Restore? I chose a point to before 13.8 installed, I think 11/1 it installed on my machine so I chose 10/30 which was the first date prior to the install.
The reason I came back to this forum - I did not play on LB for a few days after I fixed and the same exact issue happened again. The error that is happening is:
LB flashes the screen to launch and then disappears within seconds. Nothing opens, no errors.
I did all of my troubleshooting steps I listed above:
"What have I done to troubleshoot the issue?
1.) Reinstalled a fresh copy of 13.8 (before the rabbit holing began)
2.) I went into my LB\Updates folder and located the 13.7 Setup and ran, it did not end up the launchbox\launchbox install
3.) Reinstalled 13.8 again
4.) Went into my LB\Backups folder and extracted my last known config that worked
5.) Checked the LB\Logs but my last logs were from weeks ago"
I noticed that my LB updated again to 13.8. I rolled back to 13.7, went into the LB\Updates folder and installed it from there. Since none of the troubleshooting above worked, I ended up having to do another Windows Restore to 10/30. Personally, I am keeping off automatic updates in LB settings as this has happened twice, I think there might be something not playing nice IMO.
Good luck Dravin, hopefully something shakes out for you.