LO is LAX which seems great but I couldn't find a single seat in C after playing around with the truly awful M&M site that gives you an error when nothing is loaded near the scope of a search.

But bear in mind this is an airline that forgets to load its sale fares for "Crazy Wednesday" so it wouldn't surprise me if they just forgot or there are just no C seats to offer given they sold their 18 seat C cabin dirt cheap as LAX-BUD for 650 EUR o/w.

In which case why do LAX? Perhaps some contract with M&M says one longhaul per month?

In P (W) there are a few dates but most returns are just 1 seat.

WAW-LAX 08, 11, 14, 17, 18, 24, 28 MAY
LAX-WAW 24, 26, 28 APR 29, 31 (Flex) MAY