Hi Ompal,
For further troubleshooting, I would like to collect the following detailed information:
1. Please confirm whether the affected local AD user’s UPN suffix is the custom domain (here is abc.com). You can use Active Directory Users and Computers (ADUC), double click him and check his User logon name under the Account tab. Here is an example:
2. Is the affected cloud users’ status “Synced with Active Directory”? You can go to the Users page to confirm it. Here is an example:
3. From the description, do you mean that the issue occurred all of the synchronized users?
Thanks,
Claud