50 AP Free quest not appearing?

Well, originally the event lasted longer than the 7 days it lasts for the rerun, so people would have a few days to farm it. It's probably just a case of the devs not bothering to change up stuff, and in any case, it wasn't the most efficient node unless you could farm it with a full stocking team, so it doesn't really affect us if we can't farm it that much.

It unlocks after the final time gated story quest is finished. That means you only get i believe 28 hours to farm it before event ends. Originally this event was 10 days not 7 so you had a 4 days and 4 hours or 100 total hours to farm it.