This is caused by the constituents either being in a group or a household, and the import process cannot tell which record to use. To resolve you can get the system record ID's and use those to import the records. System record ID's can only be found in query and are different than the constituent look up ID. 
  1.  Get the system record ID's
    1. Option 1- If you have the record ID's in an excel file, You can import a selection of the names and look up ID's.
      1. Build your query to pull the system record ID
        1. Go to analysis
        2. Click information library
        3. Click add and an ad-hoc query
        4. Select constituent
        5. From the left select the selection folder
        6. From the middle Select the selection you imported and move to include records where and set equal to yes.
        7. From the left-hand side of query select constituent
        8. From the middle select constituent record and move to results fields to display
        9. Click the button to export to CSV
    2. Option 2- If you only have the names of the constituents in you import CSV file
      1. Build a query using constituent names to find system record ID. 
        1. Go to analysis
        2. Click information library
        3. Click add and an ad-hoc query
        4. Select constituent
        5. From the left select constituent, from the middle select constituent record more to include records where "set to is one of" and research for the constituents in your import process. 
        6. From the left-hand side of query select constituent
        7. From the middle select constituent record and move to results fields to display
        8. Click the button to export to CSV
  2.  Copy and past the system record ID you pulled in above query into the constituent field of your import excel file.
  3. Save the excel file
  4. Edit your import process to use system record ID.
    1. Go to administration
    2. Click Import
    3. Click the expand button next to your import process
    4.  Click edit
    5. To re-add the file you changed to use system record ID
      1. In the drop-down next to import course change to local file
      2. Next to file click the green arrow button and locate the import file
    6. Click map fields tab
    7. Re-map  your field from the batch template to your excel file
    8. Click set options
    9. Click other
    10.  Under search list fields select ID
    11. Click save
    12. Click the import process
    13. From the task, menu click start process