this is the only gun i have an example of, but none of the Season of the Wish craftable weapons from the Undying set can have Mementos applied to them, even if re-crafted, even if crafted months ago. Was trying to put the summer memento since this was what I used as my orb generation gun for the event, but I don't know how long this issue has been around, and I haven't seen anyone else talk about it.