Swap Cables on the Speakers and see if the reported on off centre migrates towards the other channel.
Check symmetry of the arrangement for the Speakers within the Room, Dimensions for positioning to Side / Rear Walls - Accuracy equal dimension of the Baffle to the rear wall - Accurate dimensions for the Toe In if used - Accuracy of the Plumb of the Speaker- Side Walls are expected to be perfect Plumb - Baffle is to be matching Plumb on each Cabinet - Leaning Baffle to be matched as a fall on each Speaker.
The Room used to produce the audio systems End Sound can be investigated to see what can be done to create a condition where the Speakers are very accurately Coupled to the room.