Ever seen this error when trying to update lines to add inventory detail:

message: "The subrecord line has already been committed or cancelled. The previous subrecord reference is no longer valid. You must get another reference to the subrecord in order to perform this operation.",

Haven’t seen that, but My assumption is that, the particular serialised/ lot number is either committed on some other order or it’s cancelled from the incoming record(Item receipt or Inventory Adjustment)