A large reference has been moved to another cell.
Depending on whichever cell loads first - the original cell or the new cell the reference was moved to - every temporary overwrite record in an ESM flagged plugin might be ignored and the reference load at its original position instead. In case the new cell loads before the original position, the reference is loaded at its new position and behave like a normal reference.
Object LOD for this reference is generated as if it were a normal reference so there is no gab between LOD model and full model.
This can also trigger large reference bugs in the original exterior cell.
See large reference bugs for more explanations and solutions.