In T-code: FB03, there are some unknown blank fields exist in the sreen when you click "Change layout" button.
You could add this blank field to "Display Columns"
You will find that it displayed without field name
The blank field is due to the missing translation of field PRODPER. Table ALV_BSEG contains field PRODPER in an append structure but the description in English is missing. Thus the field in the FB03 layout configuration seems to be empty but it isn't. For translating the field please proceed as described in note 1281453.
Related SAP Notes/KBAs
SAP Note 1281453: Correction of translation / Translation of missing Text