Cannot add virtual-wan-link as a normalized interface, Fortimanager 7.4.5

Hi all,

anyone aware how can i add "virtual-wan-link" SD-WAN zone into normalized interface mapping in Fortimanager ? I am able to add every other SD_WAN zone, as long as the name is different than the default "virtual-wan-link".. 

Fortimanager is running 7.4.5