Collective ownership of the means of production does not guarantee that the ostensible owners will be able to exercise the authority the ownership implies.
Ownership is just authority over material things. Collective ownership disperses that authority without necessarily enabling the members of the collective the experience of and the proper exercise of autonomy.
Engels seems to be unable to see the propulsive character of authority. He sees authority as the coordinating function and fails to see the infectious quality of authority, of how leaders drive the situation rather than merely manage the situation.
One of the chief functions of authority is to inspire. To inspire is to imbue in another a sense of their own autonomy.
Engels considers authority as the anti-thesis of autonomy whereas authority might well be considered the highest expression of autonomy. Engels views subordination as the surrendering rather than the expression of autonomy.