My AMPC's coffin simply does not persist across resets for one reason or another. I have set it in three different locations, with a DM spawning in a new coffin each time, and last time, DM Enigma used the DM Fix Character Tool to try and see if that would sort out the issue, and unfortunately, no success was had -- this message pops up every time.
The coffin isn't where it should be, each time, meaning it just doesn't appear, and a new coffin has to be spawned in by a DM or acquired vis-a-vis the merchant in the mortuary and sat down, every reset. Thing is, I did not have a problem with the AMPC I played during NCE, so this is a rather new development.