That's weird. Production is normal. So someone is buying them faster than they can go on the shelves, or stores aren't placing orders for them.
What's really strange is my sources show a shat ton of RM650x's in the Almere warehouse, but no RM750x. There's also a lot of RM850x's in stock as well.
Maybe some system builder in the UK bought them all up?
If you can buy the -EU version (CP-9020179-EU), I see there's some of those in stock.