I just tried Hard 23 again and the solution seems to be fine for me. I can help you track down the issue if you like (though I don't want to post full solutions).
First of all can you verify that this is the level you're having the problem with?
We seem to diverge on the position of a shape in the 2nd column pretty early on.
We get to here using the same logic (I think):-
But then after that my next move is:-
This is where our solutions differ. As far as I can see the only place the black circle can go in that 2nd column is in the middle, next to the 4. But you put a white hexagon there. This is what's throwing off your future placing of other hexagons.