Right, well it seems like no one can see my 3D object in multilayer even though it is activated and I myself can see it.
Also, 3D objects of which I know are owned and activated by a person are (except for, as stated before, my own item) invisible to me when I play with them online.
However this is different in single player, I see my own object and objects of others using the /lp 0/1 command.
Help would be appreciated.