system: xbox
I had this problem already at summerset event with the Alinor archway, tall.
Now it destroyed 10 skeletal marionette parts I wanted to sell for 200.000 gold.
Had listed them in a store, then removed them to sell them in another one with better location.
Just now they are suddenly bound after I took them from my mail.
With the Alinor arcs, I "turned" an unbound in my inventory by buying one from the event merchant.
There should be a marker on unbound items that avoids that they are transformed to bound during events, this is pretty annoying and can be expensive (had sold 20 skeletal parts sold for 400k gold already).