If you teleport from a monument back to your base or to another place that should be safe to log at and don't stand up before you log out it seems the game thinks you are still at a monument and player logs back in dead. We've had 2 reports of this happening now. TerminalJunker & Maddax Mcloud on US Survival. Both have lost their inventories and woke up on beach. Seems that the backpacks have been saved.
Can currently be avoided by just standing up before logging out, but Maddax Mcloud was unable to do so and thought he was locked up so restarted.