Target State

Target state Shows the state of the route. (ex. active, blackhole)

BlackHole

Above state indicates that the route's target isn't available (for example, the specified gateway isn't attached to the VPC, or the specified NAT instance has been terminated).

In this case, the target is IGW. then, the reason of this situation is that the IGW isn't attached to the VPC.)

Resolve

If you attach IGW on VPC, you can check active state.