I have a hand, where HEM claims I have an Equity of 31.4%, which when the money went in at the flop looks right.
The problem is, it's a $51.25 pot, which I won, and it also claims a EV$Diff of -$50.09
31.4% equity of a $51.25 pot means I should expect to win $16.09. That's the definition of equity. EV$Diff should therefore be -$35.16, if I understand what that field is trying to tell me.
One complication is it's a four way pot. One stack double mine, one nearly equal, one smaller. Equity when the money went in was 58%/31%(me)/8%(Smallest stack)/2%(largest stack)