Why does the solver have no bluffs here?

Usually looking at villain's response will make it pretty clear why something happens in equilibrium

Here they're folding the nuts 60.7% of the time (and 100% of the time without a heart) vs a shove because they don't have enough equity to call versus a straight+flush draw

You see a similar dynamic on other 4-straight turn betting spots where you can go for >2x overbets to make straights/sets indifferent

It's actually a really nice exploit IP sometimes because people won't donk shove enough when the improve on the river

I may be missing something but it seems to me like the reason you can’t have bluffs is because any bluff is -EV. The reason any bluff is -EV is because if you are bluffing you can run into the Qh enough for that bluff to never be 0EV and always less.

But if you don't have bluffs, how can you bet for value?

Might is be reasonable to suggest that hero's offsuit queens are the "bluffs" here? These hands are at the bottom of hero's raising range and can even be behind some hands in villain's continuation range. As I understand it, thin value can serve the same purpose as a bluff. So, we might say that hero has no bluffs here, but only thin value?

Equity before the river isnt 0%, the non heart straights are basically “bluffs”. Youre betting 7x pot so Qhxh is value vs other Q, and the regular straights are semibluffs and are behind if V has Qhxh.

The solver does what it does, and is perfect with it's range because it tried everything else and it was worse ... it doesn't "think" or "try to create a balanced strategy" in the way you are thinking about it.

In this case though I'd guess that the "balance" is around V folding the shared nuts. So H shoves a bunch of nuts+redraw hands and some nuts + blocker to redraw hands ... then V is forced to fold the plain nuts some of the time. Shoving non-nut hands would then make it profitable for V to call all plain nuts, and H would lose value.

If I am not mistaken, I see KK raised all in at a small percentage.