I can't speak for the RRS but when I first took my LR3 out on soft sand I encountered a similar experience. When it was time to replace my tires I opted for a more aggressive tire and it was like night/day difference really. The factory GY's didn't fare well.
Some will say that driver ability does play a role and I've seen evidence of that. What did you air down to? 20-25psi? Were you in Lo or Hi, manual shifting, DSC on vs off? I don't think it could be the 4wd unless your vehicle showed evidence of that in its warning lights or settings not showing correctly.
Expectations - it would be weird yes if you were on mostly flat terrain but your results could have been expected if say you were traversing sand hills, etc. I've found this blog and I'm pretty sure the user is on most LR forums but looks like a good read to me:
NextStepDesigns Blog Archive How to drive the Land Rover LR3/RRS in Sand