Sorry for getting on this older thread ...

Same problem here on 757 (4.4) and 767 (1.4): Autobrakes are set but not working on rollout, no difference if landing manually or Autoland ... they disengage at touchdown.

Any other tips or cues then reinstalling are welcome  :)

Edited: Must have been my throttle setup and handling that triggers the disengage action. The throttles must be at "idle" when touching down to enable a correct function of the system. Any forward movement and you disable it.
Reverse isn't a problem then of course.