That's the one, yes. The robot is "lost" in the sense that it's standing in a room full of identical robots, and declining to voluntarily do anything to distinguish itself, so they have to create a situation where it involuntarily behaves differently.

The scene where they finally get it, because it moves and none of the others do, works okay. But all the earlier scenes where they all move together, and the humans are going "I can't tell them apart", fall flat, because they're blatantly all making slightly different motions, starting and finishing at different times. (I guess standing still in unison is easier to choreograph than moving in unison, but still...)