If you recall Hasbro was going to make another production run of the 2018 The Black Series 59: Captain Rex figure because they seen a need for it in the market, so online retailers took preorders for it a while back, but looks like that is not happening now.
Entertainment Earth has sent out email notices to people who preordered this figure stating Hasbro will not be producing any more of him, well in the old red box. Maybe we will get a repack in updated packaging or an Archive version of him later on, guess we will have to wait and see.
“Unfortunately, we’re sorry to report that the manufacturer has notified us that we will not be receiving any additional shipments of the Star Wars The Black Series Captain Rex 6-Inch Action Figure (Item HSE0623) you ordered, because they have discontinued production of this item. No additional information was provided to us by the manufacturer as to why this occurred. Sadly, that means we will not be able to ship it to you and have cancelled it from your order. We apologize for any inconvenience this causes.”