I've had a problem with the difficulty settings. Normally, I set it customized (67-73 percent realism, depending on whether I want the event camera). Other than being unable to wrap my head around the TDC to set up firing solutions

I'm fine with 'limited' and 'realistic' everything else.
My problem is everytime I start a career, manual TDC is on. Is this because I set my career to 'hard'? There is no 'custom' setting (Medium difficulty leaves off limited fuel/compressed air which I'm fine dealing with in limited quantities).
What gives?