everytime i use matrix i grow another white hair, for example now. what the heck is "QPX Warning. Illegal faring spec: missing Boolean connective"?
Dunno. Try unchecking "Only show flights and prices with available seats" for now, just so you get a feel for it (see screenshot).
While we're at it... it's unlikely you'll find P, so here's your next tip: it appears that A3's economy booking classes are Y, B, M, H, Q, V, W, O, L, K, J, E, S, T, U, and P. So start with
A3+ / f bc=p, and then change the
p to
u, then
t, etc. until you find something.