Getting stuck on loading page (black with solar diagram on bottom right) with fresh installs of Pop!_OS and KSP

[Astro Nut]

I just got a new desktop running Pop!_OS (Linux).  The OS came installed by the manufacturer, so it's a proper install.  It is also updated.  I have been able to install Steam, play several games through Steam (Proton), and even GOG Galaxy via Lutris.  However, I cannot get KSP running.  I have tried fresh downloads of KSP 1.12.5 and 1.11.2 by downloading and extracting the Linux version Zip file from the KSP website.  Here is what happens:

1. Run KSP by double clicking KSP.x86_6
2. Properly get through the first loading stage with the monkey wearing a helmet
3. Close the 2 pop-up windows
4. Click <Start Game>
5. Click <Start New>
6. Move radio button to <Sandbox>
7. Click <Start!>

I will then get to the next loading screen with the planets spinning around Sol on the bottom right.  They freeze, and I hear the birds chirping.  The entire computer becomes unresponsive even to keyboard shortcuts such as Ctrl+Alt+Del and Alt+Tab.  I then have to reboot the entire machine using the physical button. 

KSP.log

Please let me know if you have any ideas where I can begin to troubleshoot.  I would rather avoid linking my KSP purchase to Steam so that they stay separate. 

Thank you in advance!