Sundried

Hi all, doing some GTO study here, stakes 0.25/0.5, effective stacks 50

SB opens Kh8h 1.25, BB flats A7o.

Flop 8d7d4c (pot 2.5)

SB checks, BB bets 1.65, SB callss

Turn Jc (pot 5.8)

SB checks, BB checks

River Qs (pot 5.8)

SB bets 3.83

Here the GTO decision for the BB is to call with A7 but only if holding Ad. All other A7 combos should be folded, including when holding Ac, which doesn't make sense to me as I'd think you should call when not holding Ad or Ac as this blocks the nut flush draws that missed. However for some reason the solver thinks you should near 100% call with any A7 with Ad and near 100% fold with any other A7. Could someone please explain why? As this is blind vs blind and ranges are super wide I could understand too if the solver were to call with any A7 regardless of suits but this also is not the case.