Hi! Does Lufthansa hold seat availability to release it later, or if the class has no seats, it means it's completely sold out?

I'm trying to figure out if there's a chance of getting an upgrade via miles on a flight that's a week from now, but according to experflyer it's availability is J1 C0 D0 Z0 P0 G0 E0 N0 Y0 B0 M0 U0 H0 Q0 V0 W0 S0 T0 L0 K0

Does that mean the entire flight is sold out except of 1 business seat (which means no reason to expect an upgrade), or they might open more seats during the week?