I tried to strap tow my 2001 XK8 (needs to go about 1 mile up the road) without the subframe plate installed. Transmission in neutral, but the rear wheels won't turn. Wheels can be turned by hand when jacked up.

I can reinstall the subframe but since I am taking to a shop with a lift to get fuel tank connections released (why I removed subframe originally), I thought this would be simpler for the shop.
Does anybody have any ideas what is preventin:confused the wheels from turning?