Thank you for trying this out. Yeah it's a good idea to restart your PC after running both commands. Make sure your Windows is up to date as well. You're on Windows 11 I presume ?
For the insider build, in Steam, if you click the cog wheel (manage) at the top right, then select properties and go to the Game Versions & Betas and switch to Insiders, that should put you on the latest build.
Also, I presume that you are not using any mods ?
Also, when reinstalling, have you tried to delete or at least rename this folder: %userprofile%\Documents\My Games\GalCiv4 ? Let the game recreate it, then transfer your save file from the renamed folder to it. See if that fix your issue!
Also, if that doesn't work, it may be useful to look into debug.err in %userprofile%\Documents\My Games\GalCiv4 see if there's anything in there pointing towards what could be problematic.
Else, are you using OneDrive ? Any Anti-Virus beside Windows Defender ?