Hello there,
Basically, it's a 2-step process:
Get reference to the WordEditor object
Using the clipboard, copy and paste the formatted content into the editor
The below thread discusses the same issue and you can try out some troubleshooting steps from this and see if that helps you to sort the Issue.
https://social.msdn.microsoft.com/Forums/office/en-US/f5fd2151-4738-4daa-8116-e9fb1c1b2488/problem-with-images-in-an-meetingitem?forum=outlookdev
Hope this resolves your Query !!
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