Lately I have notice a lot of people complaining that after logging in to the server ( in this case online) their base is gone and thralls are left floating in mid air. Soon they blame this on some patch.
However it could be as simple as your base hitting decay status and another player clicking on it to get destroyed.
I have seen it happen already in the past week with 3 bases in my server ( Official 1502 PVE ). Someone walks by your base notice your base is in decay phase and clicks on it to destroy it. Bang all your stuff instantly destroy. Then everyone is in a frenzy looting all your stuff. Gone! Suddenly you log on and your things are missing and you blame it on a bug. little did you know all your neighbors took your stuff and Thrall Lvl 4 Ivan the Merciful finds himself in someones else work bench. lol
To find out what happen to your base just check your base log and see what took place.