Don't custom courses expire? Not sure where I got that idea but I thought they did.
No doubt from 'experience', same as all the rest of your, uh, 'pronouncements', right?
Waaaaaaay too easy.......
Excepting a couple of courses that disappeared when Oakmont was 'removed', all of our club's custom courses remain intact and usable since the day they were created. In the OP's case, my gut says someone within his club deleted their courses.