After changing keyframes in the rotator input, the values revert back to the previously inserted numbers or are removed completely.
In other cases the tangents to and from are deleted and only the basic values are stored.
Examply keyframe I'm using:
0,0,0,20|1.2,0.24,10,0|4.5,0.4,0,100|5.3,0.55,100,0|8,0.62,0,100
After entering this as keyframes, loading the sandbox and then returning to the designer, the keyframes are gone.