A couple of months ago Outlook 2016 on my old PC (Windows 10) started misbehaving:
- Clicking “Attach File” to add an attachment from my PC to an email message;
- A window would show up. When it worked, I would be able to move the mouse down and click “Browse This PC…”. However, nowadays this window disappears so quickly that it doesn’t give me enough time to click that “Browse This PC…” item!
- Web search ensued. Some suggested repairing the mailbox, which I’ve done but to no avail;
- To get around this, open a windows Explorer window and navigate to the location where the attachment is located, drag it to the email window and release it. Viola, attachment added and you’re done!
Hope this helps!