That card isn't going to help anyone, so I'd say this another opportunity to pot it to find out if anyone has Kx of spades.

I wonder, though, if in this example checking the flop may actually have ended up helping get you action - by waiting until the turn to bet after your preflop raise, you may be seen as representing AAxx, not the flush. It may induce a call from a weaker flush, at least at a microlimit table.

(I don't know much about PLO, but I'm trying to learn)