"TableField tablename: fieldname" is a Primary Key with a subset ratio of less than 100%.  This indicates a likely missing Dimension value.

This field is a Primary Key with a subset ratio of less than 100%. This indicates a likely missing Dimension value.

You should investigate this table and it's relationship to determine if this ratio is to be expected or if you are missing important data.

Use the Flag Details, QSDA Keys view or Qlik Sense Data model viewer to investigate the keys and relationships.