Originally Posted by
Grog
If your chosen flight is showing zero upper deck seats available, something else is going on there--maybe that flight is highly desirable and already filled up (one big royal family could do it), or maybe it's not really a 747-8, or maybe you're enjoying a delightful IT glitch. Hard to say without details about the specific flight.
Does LH do that thing for longhaul where they close off the top deck to limit the number of crew needed? If they do (they did for the 747 domestics few years back) then it might also mean the business demand is low and projections point to main deck being sufficient.