Grand Chess: Can someone please explain the promotion rules? BUGS?

lichess rules page does not explain this at all.
It appears that a pawn does not have to get all the way to the last row (10th rank) to promote. Instead, promotion MUST be done when pawn gets to 8th rank. Is this a bug? Or is this the rule?
Also, when I have the choice to promote in a game, I can only get a piece that has been captured. Is this also a bug? (in other words, I can't have two queens??)

If neither of these are bugs, then what happens if nothing gets captured and you push your pawn down the board
? I tried it out on the analysis board and in that case when I moved a pawn to 8th rank and 9th rank it stayed a pawn and then it would not allow me to push the pawn to the 10th rank (since I had nothing captured and therefore nothing available to promote to)

Reading the rules at MindSports, promotion should be optional when reaching the 8th and 9th rank.

Now, if the pawn is in the 9th rank, and there is no available (captured) piece to promote to, the pawn cannot advance (but can still give check).

https://mindsports.nl/index.php/arena/grand-chess/20-grand-chess-rules

Here are the official rules on promotion: https://mindsports.nl/index.php/arena/grand-chess/20-grand-chess-rules?start=1

This shows why an option is better than an obligation: https://mindsports.nl/index.php/arena/grand-chess/20-grand-chess-rules?start=2

I hope this helps :)

okay, thanks. Richard, maybe you can link these pages on the "rules" page for chess? currently the only rule page you have does not address these rules which differ from normal chess.

Here's another article on the 'why' of the rules of Grand Chess: https://mindsports.nl/index.php/moving-forward-looking-back#grandchess