Just talked to customer support about this stuff to try and clear up some confusion.
The stuff from bundles you can't sell, when purchased, there was a discount for the items in the bundle which is why they cannot be sold.
The old clubs though, we don't know why, but that seems to have been an issue that's popped up recently. I would reach out to our support staff with screenshots of the sell equipment screen if you still would like to sell it.
https://m.wgt.com/help/request