This occurs when using the Word Merge field of the type Fill- In under the Add-Ins tab when editing your letter template. To resolve this field will need to be removed and the text placed directly in the document instead of within this field. 

To remove the field:
  1. Go to Mail > Donor Acknowledgement Letters
  2. Double click on the settings for your particular merge (parameter file)
  3. Click Send to Word Merge Wizard
  4. Select Simple Merge or Conditional Merge (if selecting Conditional double click the conditional field being used and double click the conditional statement)
  5. Click Edit Word Merge Document ,
  6. Remove this field with your text in it by highlighting the field and pressing the delete key on your keyboard (copy the text first for the next step before deleting) 
  7. Add the text to your document directly instead  
  8. Click to the Add-ins tab in Microsoft Word
  9. Click save and return to Raisers Edge to save the changes