Some rig controllers look like NURBs curves but they are actually a joint node. Joint nodes have some extra rotation/orientation attributes that, if not at zero, it makes the xform calculation more complex.

This affects everything world space-wise in animbot, such as Temp Pivot, Copy Xform, Attribute Switcher and Align Objects. It only applies when the action is target at multiple frames at once. For single frames, this condition doesn't apply, so the workaround at the moment is to apply one frame at a time.

UPDATE: This issue has been fixed on version 1.3.0.