Hi, everyone!
I have this issue, too, but only when trying to send an MS Outlook Group email to Evernote, i.e. when I'm in the Group folder versus my standard inbox. The add-in works great when I work out of the inbox or one of its subfolders.
Also, and perhaps related to that, I have noticed that the option itself (to send to Evernote) doesn't appear by default. I have to go into Customize and check off the box to use Evernote that way. When I'm in my normal inbox, the Evernote add-in pops up with all the other apps, such as OneNote, etc. So, I wonder if this problem is connected to Admin security settings related to Groups.
Hopefully, this will help with debugging!
All my best,
Tom
Ps. Here is the error message I receive! ⤵️