Why is auto import not available for Vanguard?
If Vanguard is in the top left area of the form, use Vanguard (brokerage).
If Vanguard is in the top right area of the form, use Vanguard Group - Mutual Fund Account.
If you are using TurboTax Online, try importing using a different browser. Make sure any VPN or Anvi-Virus is turned off.
See the following TurboTax Help articles for potential fixes: