On this particular computer, I use iTunes 11 only with my cloud purchases – I don't have any music stored locally. Very often (but not always), when I launch iTunes, it comes up with an empty library because the preference setting to display cloud purchases is switched to off.
I keep switching the preference back on, yet it keeps disabling itself again in the future. Is there any way to get it to stick?
Update: even weirder, sometimes when this happens the checkbox to show or hide cloud purchases (in Preferences > Store) actually disappears. Literally, I go into Preferences and it simply isn't there. If I quit and relaunch multiple times, eventually it comes back and then I can reenable it. I'll take a screenshot the next time this happens.