Sending, receiving, and organizing email in Outlook.com
Sorry to hear that you are having trouble with attachments in Outlook on the web. Since you can see the attachment when opening the same email on your phone, could you please provide a little more information to determine whether this is related specifically to Edge or to the Outlook web interface?
When you open the email in Edge, is the attachment completely missing, or do you see an attachment icon/name that you cannot open or download? Does this happen with all emails containing attachments, or only certain senders or file types? Have you tested the same email using an Edge InPrivate window? Are you accessing the account directly at Outlook.com?
If possible, please share a screenshot showing how the email appears in Edge compared with your phone, making sure to hide any personal information.