I have not been, Alt + Tab 'ing out or leaving during the loading process. But I did run KSP elsewhere, multiple places, no change. :< I also had all permissions on all the folders. I eventually got it to work through a solution on steam, indirectly. I deleted appcache, and restarted my computer. No difference, but the appcache folder wasn't reinstalled like it was supposed to be. I just decided to uninstall and then reinstall Steam. Then reinstall KSP. It worked! There is probably an easier solution. Luckily I backed up my KSP saves, lol.
