Why username and suffix are merged in the first field of User logon name of Active directory

[MohAbidi]

Hi,
Hope everyone is safe and well.

We have synced the local active directory to azure by azure ad connect.

All usernames in azure active directory became userorganisation.onmicrosoft.com

I could not separate username from UPN suffix, I started to correct manually the issue per user but as we have several users in the active directory is there a way to correct the username of all users?

Can anyone please advise how can I do that.

Best Regards.

[#2]

Hi,
Check the AAD connect attribute sync details, attribute details looks incorrect. Validate the attribute details then test it by syncing with one user.