After a bit more digging, it seems that after coming back from LHR, it is doing a rotation to CDG
I have checked multiple days and the schedule seems to be quite consistent.
IB711 MAD-LHR 6.55-8.50
IB712 LHR-MAD 9.15-12.40
IB589 MAD-CDG 15.50-18.00
IB590 CDG-MAD 19.30-21.40