9.3. File selection dialog doesn't have Attach Plus button
After working properly for some time, clicking the Attach (or paperclip or Insert) button in the email application brings up the applications regular file selection dialog instead of the Attach Plus file selection dialog (in other words, the Attach Plus button is missing from the file selection dialog).
Before continuing, please make sure that Attach Plus is actually running and that the problem still happens.
If a plugin to Outlook has changed the behavior of the Attach button, it will prevent Attach Plus from properly intercepting the mouse click.Â We know for certain that Winzip has an Outlook add-in that causes this problem.
To test, launch Outlook in Safe Mode and see if the problem goes away
Also, refer to the following related articles:
Uninstall the Outlook add-in that is causing the problem