It's a rare occasion when I change my project filter to something other than "Remaining." Earlier this week, I had such a rare occasion. I guess I have never noticed the other filters beyond "Remaining" and "Active."
After toggling between "Stalled" and "Pending" a few times and not seeing any projects appear, I got curious as to what those filters do. The answer was in the manual but I didn't find it as obvious as I would have thought it'd be.
The criteria each selection filters on are:
From the OmniFocus manual:
You’ll probably want this to be Active most of the time, so you can see only the projects you’re working on now. You can also choose Remaining (projects that haven’t been completed or dropped), Stalled (projects without any available actions), Pending (projects with start dates in the future), On Hold, Dropped, Completed (projects you have marked with these statuses), or All.