To filter for iso pots (limp call) postflop, disable "Standard Preflop Only" in the settings popup and then enter "RC-R" in the line input that shows up
A spot like X-X-XF or X-X-XC will show the average size they folded/called against, not the average size which IP bet
Often the frequency for a spot will add up to more than 100% because a player's raise frequency excludes facing a jam (where it's impossible to raise)
More often than not, the "bluff EV" vs a GTO opponent is not 0. For example in this sim, OOP is folding much more than the 50% which would cause a 0% bluff EV vs a pot size bet. If the river completes the flush the XF frequency goes down vs the same size. Or going back to facing the flop XR, IP folds less than the ~60% (10.9/(10.9+5.5+1.8)) which would cause a neutral bluff EV, since OOP can use bluffs with equity
The "call EV" however should be close to 0 in all spots since we adjust what hands are considered bluff catchers. Data can differ from 0% due to low sample size or blocker effects, and a few lines like B-BC-R are very hard to distinguish so the threshold is off