Hi @Jayne ,
Welcome to our forum!
Does this issue occur recently? If so, have you done any specific operations before that?
Considering that it may be caused by the damage of the profile/data file in the Outlook client, it is suggested that you could try to create a new profile and add the account to check if there are some differences:
- Create a new Outlook Desktop profile, Create an Outlook profile.
- Add your Outlook.com account, Add an email account to Outlook.
Hope to help you!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.