UPDATE :
Well, I've noticed that if one player is still connected, objects are as they should be for future players.
However, if everyone disconnects, nothing is saved on server and future players won't see the objects as they were before the last player has left the server.
Before I report this issue, everything was saved one the server, and even if every players had disconnected, the next one to connect would see the obejcts as they were before...
Is this a Tnet update ?...