Teaminbox attachments are blocked for one user

Teaminbox attachments are blocked for one user

One user in our team can no longer download attachments from Teaminbox. Details:
  1. User can download attachments from Zoho personal email
  2. Attachments from Teaminbox are blocked (see attached)
  3. Issue happens in different browsers
  4. Issue only impacts one single user
  5. No browser settings or Zoho configurations have been changed recently
Error:  "The content is blocked. Contact the site owner to fix the issue."