In your controller tags, if MCM.Config.ModDef.ErrStatPtr is 0, then status data is likely overwriting the first 33 words of the MCM's ReadData or WriteData arrays which would typically be used for Modbus data.
Enter a value of -1 for this variable if status information isn't being used. If it is being used, then enter a value that corresponds to an unused Read Data address. Toggle the MCM's warmboot tag for this change to take effect.