After installing 3.012 update today my BOS would not complete game loading. Progress bar would freeze at far right edge just before finishing. I completely disabled my security/antivirus/firewall software and loaded the game completely this time. With the game still running, I restarted all the security/antivirus/firewall software and ran a mission again.
At this point, I closed Steam and BOS. On my next attempt to run a mission, the game fully loaded and works fine now with security software running.
Muscat, I don't know if you've tried this process, but offer it since it did solve my problem.