There's no point in messing with the Lobot shot. None.

It's a perfect deception; Lando is leading his 'guests' into a trap.

Lobot, walking by in front up the stairs is the marker for the timeframe in which Lando will have Han and Leia in front of Vader.

I always believed after passing in front of Lando and quarry, walks to the holding area where Vader's troops are waiting and gives them the signal.

Lobot walks off screen, we do not see where he goes - we do not need to see where he goes. He goes to get the stormtroopers.

No continuity error in that shot whatsoever.

None.