I worked with support as Leizy suggested.  I was informed that this has become an increasingly problematic issue the past week or so.  Both QB developers and Microsoft engineers are aware of the issue and are working for a resolution.  Until then, there are two workarounds.  I'll add those in the hopes it will help someone else.

1. When the email initially opens in Outlook, save it as a draft.  Close the original email and reopen it from the draft folder.  You can then edit and send the email.

2. Save the attachment from QB to your computer.  Open a new email and enter the address/text, then send.

Both ways work, but IMO option 1 is the easiest/least steps.