The 'Import Portfolio' section comes with certain limitations due to data brokerages make available for import.

For instance: 

• Your account won’t have access to features like NAV, Decision analysis
• Information on the ‘Buy date’ of your holdings, as well as the options to edit or delete holdings. 
• The 'Transaction' history to check the P&L of your portfolio.
• Information on the 'Rolling returns' of your portfolio.
  
  

This is because brokerages only provide current holdings via portfolio import, and don’t provide historical transactions data.