I ran into the same problem and might have found a solution, I knew this could not of been a OBS problem, because I only updated my Nvidia drivers not too long ago, I run the beta drivers of Nvidia Geforce experience which allows me to record separate audio tracks (one for game sound and one for my mic) there was an update for it... OBS studio would crash whenever I press alt + F10 to record the last 10 minutes of gameplay, it was working flawlessly with the previous Nvidia Geforce experience beta driver, not sure if this will work for everyone tho
I uninstalled Geforce experience and uninstalled the Nvidia display drivers using DDU, I downloaded the latest Nvidia display drivers and installed it, I also downloaded the latest Geforce Experience beta drivers and installed it, tested it last night, jump into Titanfall 2, started streaming at 720p 60FPS and 2000 bit rate, played one round, hit alt+f10 to save the last 10 minutes of gameplay and no problems
Sorry, I know this is an old post but I thought this might help someone