I found this bug while i was animating a limb that needed the bend positive or negative option animated within the time line. When I'm in animate mode and the bend option for a constrained joint is first keyed in the opposite position from the original set up pose and then later keyed back. The first key will not stay set, it will flip it back to the original bend position but still show that it is keyed.
If you can fix this problem soon that will be awesome, I've found a makeshift way around it but its only a temporary fix.
