@Pharan - thanks for the quick response. I am using v1.7.12 (latest) and there only seem to be "Stepped" and "Interpolated" options for Playback and no longer for the key itself. Any clue how to check if this key is set to stepped?
I am working with keys at 80, 95, 105 in my timeline. All three are Translate keys - and they are each different than the last. Leading up to 80, everything plays fine (5 different Translate keys) ... after 80, no matter what I do I cannot get it to tween to the next key frame, it plays as if stepped. I delete both keyframes and recreate them manually, same result. Between 95 and 105, normal again.
In all cases where I have seen this, there is a key at 0. I always start animations by setting all bones to have rotation and transltation key frames at 0 and the end of the animation.