That is the lock position detent/alignment part of the lock ring.
If the lock ring still has a full unbroken circumference , the detent
alignment marks are not needed. Just make sure you have turned the ring to the lock position after harness is plugged back in.
I believe "Lock" is clockwise..

Look close at the Marks in the pic. One is lock, one is unlock
[ the little lines on the piece you referred to as "Ear"