I'm trying to set up a new meeting poll, but I keep getting an error message.
"We are having trouble finding one or more recipients. Please try-adding them or recreating the message. If this issue persists, please contact us."
This issue has been fixed! (in Outlook for Windows build 16.0.13408 or later)
I saw the same bug today. Mine was generated from doing a Reply All to a previous meeting in the Outlook calendar. I had then moved the CC people to the To line. But that was not the issue as even restarting Outlook did not fix the problem.
If you look in the right pane it will show you icons that you can hover to see which people are seen by the system. As a workaround, I figured out which 4-5 people were not visible there, and manually deleted them from the message recipients and simply re-added them and F/T found and added them in the display. Just a workaround. Hope this bug is fixed soon.