This is still a current issue, and it’s becoming more and more difficult now that the catalog is having more and more UGC Limiteds created.
In the DevForum post about the release of UGC Limiteds it states:
How are developers supposed to monetize off of this opportunity if we are unable to sell items from in-game?
No matter what the ID is, I cannot sell limited items from in-experience. Please fix this ASAP as it’s becoming a huge inconvenience for players, and us developers are losing a large opportunity for revenue.
Hey everyone, thanks for flagging! We got a little ahead of ourselves in the documentation for this feature but this is (temporarily) intended. In the next few weeks we plan to release an update that will enable in-experience purchasing and the seller share for UGC Limited items, so stay tuned.