Already backed up Azure VMs doesn't appear in Azure Backup tab in WAC

Dear Community !!
I've Azure VMs that are already backed up in the Azure backup service.

Despite, when I've added those VMs in WAC :

• In the overview tab, Azure Backup Status is : unprotected
• In the Azure Backup tab, it tells me to configure Azure Backup.

Is there a trick to see already backed up Azure VMs in WAC ?

Or I must register VMs to backup again ?

Thanks' for your answers,