This is more than likely due to a filter that has been placed on the one of the categories in that section of the record. On the section of the record that you are viewing each column can have a filter placed on it. To check for these filters and clear them, do the following:
  1. Go to the section on the record where the issue is occurring
  2. View each of the columns filter icons, they appear as a funnel icon
  3. If the a funnel icon is green you will need to clear it it or change the setting in order for your data to display
  4. To clear or change the setting, click the funnel icon
  5. Either click Clear filter or adjust the settings and click Apply
  6. Your data should now be visable