By default, it takes between 24 to 48 hours for Exchange Online to re-synchronize the address lists and all users to download the most updated information. Unfortunately, the commands available in Exchange on premise to update the Address Lists are not available in Office365 – Exchange Online.

https://technet.microsoft.com/en-us/library/aa997982(v=exchg.160).aspx

Therefore we will need to force that sync manually. Updating the Address Lists, requires requires to have the Address List Management Role. By default in Exchange online, the Address List role isn’t assigned to any role groups.

1 – Connect to Exchange Online

$UserCredential = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session

2 – Create a new Group Role

New-RoleGroup -Name "AddressList" -Roles "Address Lists" -Members Account@domain.com

3 – Run the Following Commands to update the lists

Get-AddressList
Set-AddressList -Identity "All users"