Minecraft Forge modification not working on dedicated server for non-OP players

Question

today I tried to test my modification which adds two ContainerBlocks on dedicated server. But I noticed that for some reason these blocks work only for players that are set as OP (operator). When I am not OP I can't place these blocks. And if they are placed (by OP player) I can't use them (GUI screen won't open).

In singleplayer this modification works fine and on server for OP players this modification works fine. So it seems like the matter of server settings or something.

Could somebody please help me out where could be problem?

Answer 1

So the problem wasn't in modification. I just totally forgot about spawn chunk protection which was causing this issue.