i success the event " NEW! Invite a Friend" between time event
this is ref: https://treeofsavior.com/page/news/view.php?n=1455#
but today am play game i dont see some item such as [Event] Unlock Voucher Selection Box x1 it disappear-*-
help me plz! thxxxxxx
they had an expiration date and were removed after their event time expired…
- Unlock Vouchers and Weapon Selection Boxes obtained from this event will be automatically deleted at the end of the event period. Weapons obtained from the boxes will not be deleted, but they will remain character-bound and untradeable.
this, in particular what some people missed, including me 
i remember reading similar post before.