A company has established a new AWS Direct Connect connection linking its on-premises data center to the AWS Cloud and configured a private VIF on this connection. Despite the physical connection status showing as UP and RUNNING in the AWS Management Console, the private VIF status remains DOWN. The network engineer confirms the ARP entry for the VLAN interface associated with the private VIF is visible on the customer's Direct Connect router. What potential issue could be causing the private VIF to remain in a DOWN state?