There is a bug in this preset where diagonal moves are highlighted for black's pawns, although they aren't accepted if you try to play them.
I tried the following sequence of moves and didn't detect that problem:
1. P g3-g5
1... p f8-f7
2. P g5-f7
2... p e9-f7
I also tested en passant with this series of moves and again found no problem:
1. P g3-g5
1... n g9-i6
2. P g5-g6
2... p h8-h6
3. P g6-h7
3... p f8-f7
4. B f3-i6 // - Check! -
4... b f9-h8
5. N g2-i3
5... p f7-f6
6. P e4-e6
6... p f6-e5
So give me a position or series of moves leading to a position where you encounter the problem you described.
I tried the following sequence of moves and didn't detect that problem:
I also tested en passant with this series of moves and again found no problem:
So give me a position or series of moves leading to a position where you encounter the problem you described.