Player Data is not saving on my realm

Every time I log in and out my character location is reset to the last log in location, and the world stays the same, this is also happening to all of my friends

Any new building we make stays, but our inventory and locations keep being reset to one fixed spot.

We assume it has something to do with player data not saving properly.

Please help.

While writing this we also noticed that in the more recent log ins its been reseting our achievements.