There is no need for engine analysis for KQ vs.K.
Espescially if the engine is going to give you a -37 evaluation. 
There is no need for engine analysis for KQ vs.K.
Espescially if the engine is going to give you a -37 evaluation. 
The engine is only going to depth 23. If there isn't mate in 23 it's not going to show mate.
I was more concerned with the minus sign. That means that the engine thought Black was winning. Odd, since White had the queen. (Btw, can't the strong side win this ending in 23 moves? Or is that 23 ply?)
There is no need for engine analysis for KQ vs.K.