If you're seeing the button is grayed out on your team account, then you would want to talk to the team about that as it would be on their end of things and not StubHub. But, a few things it could be is that those particular tickets may not be allowed for resale, the barcodes aren't available, or the team site is having any issue at the moment. Talking with them can help with this to narrow down the options for you.
One thing you could try as well is to check and see if you need to relink your StubHub account with your team account. Try those but send a private message to me or any moderator if the issue continues.