Hello fellow chessers. I'll be brief. On 10. I tried to long castle, but it wouldn't let me. What the heck was I missing? I'm posting in this forum in case this is a support issue. Thanks

The black queen is attacking the d1 square.

You can't castle "through" check.  The Black Queen is attacking the d1 square, so in order to castle long the White King would have to castle "through" the Black Queen's check on that square, which is illegal.

the rule says: "There can be no opposing piece that could possibly capture the king in his original square, the square he moves through or the square that he ends the turn. "

Wow. I can't believe that in all my years I have never caught that. Thanks to you all for setting me straight.

Good Post!