One of our users seems to be having the same problem many other folks here have. In both OWA and Outlook, and on any computer, when the Outlook Customer Manager panel starts loading an error is given that says "Something Went Wrong Please Try Again". Hitting retry does not help. We've deleted and rebuilt the Outlook Customer Manager group in O365, we've unassigned and re-assigned OCM licensing and the add-in, we've cleared cookies and browsing history, all with no effect. Though OCM does work without issue for several other users in the organization.
May I know whether this is your first time lauching OCM or it worked well before?
In addition, since you mentioned that other users are workable, please try the affected user account on any of the workable machine and check it again. This can help check whether the issue is related to the affected user account or machine side.