Case refer to http://community.office365.com/en-us/f/156/t/241373.aspx
A1: Do you mean that all the accounts has been synced to Office 365 online and assigned Lync online licenses, but some of the accounts can't be used to login to Office 365 online portal?
Yes, two OU account synced to Office 365 online, without sync error.
But I don't know how many account can't login , I just test to create a Account in Local AD , after synced and applied licenses. The account still can't login. I tried to use powershell to change password , It can login. So i guess to password is not sync .After that ,I have tried to change password in local AD. and the FIM show the password update success , but can't login using the new password.