SeamLandCrv does not have a related Generation/StructOperation AE.
The Seam Landing Curve is missing its relationship to either a generation AE or a Struct Operation. Because the curve does not know how it was created, it also does not know what to provide to you; therefore, deleting it is the only expected option.
What You Should Do
Ask your database administrator to back up the model.
Run the Clean Database custom command to delete the object.