Sometimes BOX doesn't appear to render correctly in Salesforce and a User may see this error: 

This could be a result of needing to reset your 2-Factor authentication in BOX. Use the following steps to reauthenticate.

• Open Salesforce, navigate to the circle icon on the top right of the screen
• Click it, a menu should pop up with your user information
• Click 'Log Out'

• After logging out, navigate to the following URL: https://account.box.com/login
• Log into Box (using your IPRO email)
• Complete the MFA steps to log in (most likely an email code)
• Navigate back to the iPro Salesforce website here: https://ipro3.my.salesforce.com/
• Log back into Salesforce
• Go back to what you were working on and open the Files tab, Box should load