I was in the nether and found a bastion so i landed on the corner, placed some few blocs and managed my inventory, during that time i got killed  and respawned at world spawn (i had just set my spawn point  on a bed far away so i dont know why it did that) so i then went back at the coordinates in the nether to get my stuff. Not only did my items disapeared (they were not in loaded chunk, at least 500 blocs from the nearest loaded chunks) but also the placed blocs were not there anymore, as if it never happened. I dont know if it has something to do with realms but it is not the first time already created chunks reset themselves even after being modified. I saddly would like to link images too but you would only see an empty floor. Please i seriously dont know how realms can be broken that much.