Don't ask how we got to this but a couple of weeks ago my son (an Agronomist who does a lot of off road and on road work) put a pair of Goodyear EfficientGrip SUV tyres on the back of his FL2 to replace the worn out rear Wranglers. His front ones are Wranglers with a decent amount of tread.
He came back this weekend complaining about the absolutely shocking off-road handling of these tyres on wet grass fields and in mud and how it had totally altered how the car behaved with the back end sliding all over the place. On road the handling was fine. As we have identical wheels he now has my rear slightly worn Wranglers and I have his new ones as I don't go off road much. (the things you do for your kids).
So be warned.! 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Big No No!
Even more so on AWD.
I've said it B4, Don't mix tyres and don't rotate.
Even more critical for A/T Style tyres with aggressive tread geometry. MY15
Tyre Pressure Monitoring System (TPMS)
Surround Camera System
InControl Apps soon to be replaced with CarPlay (WIP)
Meridian Premium Surround Sound
Digital Audio Broadcast
Timed Climate
Cruise ECO Data
Follow Me Home Reverse
Extra Features Menu
Picture In Motion
4x4i screen (WIP)
Digital Broadcast TV
Meridian Rear Media with WIFI
Factory Powered Tailgate
Blind Spot Monitoring (BSM)
Reverse Cross Traffic Alert (RCTA)
Electrochromatic Wing Mirrors (WIP)

Not surprised at all.

Good Year advertise the Wrangler HP as having some basic off road capability as well as all season capability with the Efficient Grip as a road only summer tyre.

I guess your son has just proved that it isn't just manufacturer hype!