New Outlook for MAC - CPU issue when using Move message

Hi I have a user who is having CPU maxed out when she tries to move a message. The CPU will go full 95% steady and the beach ball will appear making choices impossible. This only apprears only in the "New Outlook" and not in the traditional interface.

Running 11.6 (BigSur) with Outlook 16.54 on a iMac 2017  i5 - 16GB of RAM and SSD drive

Anyone else seen this issue ?