If you are on version 7.71.936 or lower: Download and install the latest version and patch, if applicable. 

If this is still an issue:

Try each of the following steps in order until the issue is resolved:

  1. If adding a phone number, ensure a phone type is selected
  2. Tab to the next row in the phone number grid or the batch. The format is applied once the cursor is in the next row
  3. Select the appropriate phone number formats in Configuration
  4. On the constituent or relationship record, ensure the phone number has 7 or 10 characters
  5. Remove the following characters from the phone number: /, -, or x
  6. Download and run the Apply Phone Formats plug-in
  7. Refresh the phone number format using Import:
    1. Create a constituent phone import file in Comma Separated Values (CSV) format
    2. On the Fields tab, select:
      Address Import ID
      Phone Import ID
      Phone Type
      Phone Number
    3. Click Create Now
    4. Import the CSV file using a constituent phone import
    5. On the General tab of the import, select Update existing records
    6. Click Update
  8. Delete the phone number from the constituent or relationship record and re-enter it