Sur le wiki j'ai trouvé un truc qui pourrait correspondre :
« Characters can be semi-corrupt and still be able to mine, kill enemies, etc. but cannot move anything in their inventory or it will disappear, and any changes in items will disappear once the world is closed. If a the player is a mediumcore character, then no items drop on their death, but will then have a completely empty inventory. If it happens once, after a while, more characters will become corrupt. »
http://wiki.terrariaonline.com/List_of_known_bugs
Ça serait un corruption en partie du personnage, on ne sait pas d'où ça vient.
Et malheureusement il semble ne pas y avoir de solution.