"Max was back with everyone else on Thursday and he was full of the joys of spring," Grayson told the club's official website.
"He's fantastic to work with and got stuck right in just as you would expect.
"Unfortunately you can't stop speculation. It shows the calibre of players we have, but there's been no written offers for Max.
"As I always say, any deal outgoing would have to be to the benefit of the club, that's why Kasper went to Leicester.
"If someone offers mega money for a player you always have to weigh up if it's for the best, but we don't have to sell.
"There's so much speculation, too many people get carried away with it. It's easy to put a headline in a newspaper.
"With any deals we do, either in or out, we will do them as quietly as possible."