When playing on my server everything was working fine until I did a small clone of a structure. After I did the clone everything seemed to be working fine other than the clone deleted the stairs on the structure but I just put them back. Then my friend came over and he said that could still see the original before the clone and until he logged off and logged back on (Picture 1 from his View). After that things just kept getting worse. Soon it was happen often where my friend would have to log off and back on to see what I was building even though I stopped using the clone command. Then I started placing stairs for the roof and they weren't even saving. I would log off and back on and they would be gone again but they would still have a glitchy hit box (Picture 2 is me charter getting stuck on the hit box from my friends view). So then I took it and put it in single player, remove the whole structure cloned and placed some blocks. They saved and everything was working. But now whenever I place stairs, no matter where I am they don't save and they don't even leave behind the hit anymore. I am not sure exactly how to reproduce this but the clone command I did was on masked and move modes.