WHY IT HAPPENS
Your bag is handled a dozen times between your cabin door and the floor of the luggage debark hall (the room in the terminal where bags are laid out by tag number):
corridor, lift, cage, ramp, cage again, then laid out by hand. It is a paper tag
and a bit of string doing all that work.
Tags come off. That is the whole mystery. A bag with no number cannot be
laid out under a number, so it goes somewhere else — which is exactly where
you are about to look.
Have photos? Say so now.
If you photographed your bags before you handed them over, that changes everything.
We can put those pictures in front of every agent working the luggage debark hall within
minutes, instead of thirty people searching for "a navy blue roller, about
this big."
Tell the porter who comes to you, or show any agent the photos on your phone
— do that before you carry on searching.
Neither of these helps you today, and both of them would have. Do them before the
next sailing while you still remember standing here.