Outlook 2016 stops responding when I click on a new meeting invite

When I click on a meeting invite in Outlook 2016, it stops responding. I am not experiencing this issue in Office 365.
What I've done so far:

1. Deleted user's OST.
2. Deleted users mail profile.
3. Repaired Microsoft Office.
4. Disabled cache mode.
5. Started outlook and safe mode.
6. Removed Add-ins.
7. Confirmed Windows up to date.

None of these fixed the issue.

Any further troubleshooting steps would be greatly appreciated!

Thanks in advance.

Is the connected account to Outlook running through a O365 profile?

Does the user experience the same issue on another PC?

Masterchiefxx17 said:

Is the connected account to Outlook running through a O365 profile?

Does the user experience the same issue on another PC?

Hello Master Chief,

Thank you for your response.

The users account was created on our on premises Active Directory and synced to Office 365. This issue also occurs on other devices.

Sounds like something went through with the sync to the cloud. If you take ownership of the mailbox, can you remove the account from O365 and restart the sync process?