[Lucky Clubs]

I don't call here.

Obviously, it's closer if the river brings EITHER a potential flush OR a board pair, but when it brings both, the range of hands that beats you is wide enough that I'd fold even with these odds. MP1's passivity makes it even more likely that he was check-calling a set, two pair, or a flush draw.

The real clincher for me is position. If I check a river and my opponent bets, I will sometimes call if the opponent has shown willingness to make a play at the pot when I show weakness. But MP1 has bet out here, and the likelihood that it's a blocker bet with a weaker hand pales in comparison to the likelihood that this particular river hit his check-calling range on the flop and turn very hard.