Users not showing in SharePoint Org Explorer Web Part, but do show in Team App

We have several users who are not showing in the SharePoint Org Explorer Web Part, who do show in Team Org Explorer App.

They are all users who were migrated into our Office 365 tenant from another Office365 tenant. 

We have checked the usual things, manager configure etc. and confirmed that there SharePoint profile is identical to working users. 

If I search for the user in SharePoint and then select organisation and I can see the user and their manager and subordinates.   Out IT team, who are very good have not been able to fix this. 

Anybody seen something similar before? Any help would be much appreciated. 

Kr and thanks.