Elixir v1.0 fails to find move

[tissatussa]

i noticed a similar case in #56 : again it seems Elixir v1.0 can easily find a good move but in the real game it made a blunder : it played 21.Nb4 ? after 4.2 seconds, but after the game i let the engine think about that position and it never considers 21.Nb4, only Ne3 (which is a good move according to SF 16) :

FEN 5rk1/pp3ppp/2nr4/3Np3/2B5/2PP1b2/PP3P1K/R5Q1 w - - 0 21

Replay the game

[ i'm on Xubutu 22.04 ]

[Event "engine vs engine"]
[Site "Holland"]
[Date "2024.06.14"]
[Round "?"]
[White "Elixir v1.0"]
[Black "Arcanum v2.1 noNNUE"]
[Result "0-1"]
[ECO "B01"]
[GameDuration "00:07:57"]
[Opening "Scandinavian (centre counter) defense"]
[PlyCount "88"]
[TimeControl "180+2"]

1. e4 {+0.21/24 10s} d5 {-0.55/12 8.1s} 2. exd5 {+0.45/24 9.1s}
c6 {-0.84/12 7.9s} 3. dxc6 {+0.60/25 11s} Nxc6 {-0.90/13 7.7s}
4. Nc3 {+0.61/24 14s} Nf6 {-0.27/13 7.5s} 5. Nf3 {+0.52/22 15s}
e5 {-0.19/13 7.3s} 6. Bc4 {+0.64/21 6.4s} Bc5 {-0.08/12 7.1s}
7. O-O {+0.62/22 7.6s} Bg4 {-0.01/12 6.9s} 8. h3 {+0.75/21 6.3s}
Bh5 {-0.20/12 6.8s} 9. d3 {+0.71/21 10s} O-O {-0.39/11 6.6s}
10. Bg5 {+0.72/23 6.6s} Be7 {-0.47/12 6.5s} 11. g4 {+0.94/21 6.1s}
Nxg4 {-0.50/12 6.3s} 12. hxg4 {+1.90/20 5.3s} Bxg4 {-0.55/14 6.2s}
13. Bxe7 {+1.75/24 5.4s} Qxe7 {0.00/14 6.0s} 14. Nd5 {+1.48/24 5.6s}
Qd7 {0.00/13 5.9s} 15. Re1 {+1.50/23 11s} Rad8 {0.00/11 5.8s}
16. c3 {+1.52/24 5.4s} Bh5 {-0.11/12 5.6s} 17. Re3 {0.00/25 14s}
Qg4+ {-0.16/11 5.5s} 18. Kh2 {+2.09/17 3.8s} Rd6 {-0.48/12 5.4s}
19. Qg1 {+2.28/22 6.0s} Qxf3 {-0.58/13 5.3s} 20. Rxf3 {+2.12/26 4.2s}
Bxf3 {-0.78/13 5.2s}

21. Nb4 {+2.07/26 4.2s} Nxb4 {0.00/12 5.1s}

22. cxb4 {+2.03/26 4.6s} Rh6+ {0.00/12 5.0s} 23. Kg3 {+2.21/25 4.3s}
Bc6 {0.00/14 4.9s} 24. Qd1 {+2.47/22 3.1s} Rg6+ {0.00/13 4.8s}
25. Kh3 {+1.62/20 6.8s} Rh6+ {-0.01/12 4.7s} 26. Kg4 {+0.82/21 5.1s}
Rg6+ {-0.01/12 4.6s} 27. Kf5 {+0.44/20 2.9s} Re8 {-0.01/13 4.5s}
28. f3 {0.00/23 5.3s} h6 {+0.75/11 4.4s} 29. f4 {+0.74/22 3.8s}
Rf6+ {+1.13/11 4.3s} 30. Kg4 {0.00/22 2.6s} b5 {+1.27/12 4.3s}
31. f5 {0.00/22 4.7s} bxc4 {+2.21/12 4.2s} 32. dxc4 {0.00/25 3.0s}
Be4 {+1.92/12 4.1s} 33. Qa4 {+0.27/21 2.5s} Rc8 {+2.22/12 4.0s}
34. b3 {0.00/19 3.2s} Bxf5+ {+3.29/12 4.0s} 35. Kg3 {-1.31/20 2.5s}
Rd8 {+3.20/13 3.9s} 36. Rg1 {-1.35/23 2.3s} Be4 {+8.15/11 3.9s}
37. Kh3 {-4.64/21 2.2s} Rf5 {+8.90/11 3.8s} 38. Rg4 {-5.28/20 3.4s}
Rd3+ {+M13/12 3.7s} 39. Rg3 {-M12/30 2.4s} Rh5+ {+M11/12 3.7s}
40. Kg4 {-M10/43 2.1s} Bf5+ {+M9/12 3.6s} 41. Kxh5 {0.00/46 6.9s}
Rxg3 {+M7/14 3.6s} 42. Qe8+ {0.00/46 6.2s} Kh7 {+M5/15 3.5s}
43. Qg8+ {-M4/31 2.0s} Kxg8 {+M3/14 3.5s} 44. b5 {-M2/64 0.17s}
Rh3# {+M1/11 3.4s, Black mates} 0-1