Hi All,
I maybe found myself :)
On the AD site and services, go on the NTDS Settings properties of one of my server with this strange behaviour, go on attribute editor then the not well updated attribute is msDS-Behaviour-Version
I found this article, at the end they changed manually the attribute
https://social.technet.microsoft.com/Forums/ie/en-US/91f7e8ab-b96f-4190-a289-801c005873c9/issue-with-msdsbehaviorversion?forum=winserverDS
In doubt, I also rebooted my 4 RODC and verified the replication went fine.
Now on Active Directory Domains and trusts, I could now Raise the Domain Functional Level
I'll force the AD partition replications
(Get-ADDomainController -Filter *).Name | Foreach-Object {repadmin /syncall $_ (Get-ADDomain).DistinguishedName /e /A | Out-Null}; Start-Sleep 10; Get-ADReplicationPartnerMetadata -Target "$env:userdnsdomain" -Scope Domain | Select-Object Server, LastReplicationSuccess
Then on the afternoon, I'll raise my Forest Functional Level.
Hope this resarch could help someone, one day.
Regards,