Hi Timmy,
Thank you for posting your problem, I am here to help you today. Possible caused of this issues with account sign-in, corrupt Outlook profiles, corrupted or outdated Outlook versions, incompatible add-ins, or issues with the Office installation itself.
To fix this try this steps: Repair Office Installation:
If Using Windows 10: Go to Control Panel > Programs > Programs and Features. Select your Office installation, then click Change. Choose Quick Repair first. If the issue persists, try Online Repair.
If Using Windows 11: Click Start button then search for Settings. Open Settings and click on APPS then click installed apps. Search for Microsoft 365 apps. Click the 3 dots then choose Modify. Select Quick repair and wait for the repair to be completed. Restart your device and try again.
looking forward to helping you out. If you need more help please let me know. If the answer is helpful, please click "Accept Answer".
Best regards, Jansher