The Mergeable Orders widget on the ShipHero Dashboard only shows orders with a pending default status, not a custom status.
Finding All Mergeable Orders in ShipHero
When you need a more complete overview of possible order merges, we recommend that you instead use the Orders page at https://shipping.shiphero.com/orders/merge/.
This will provide a detailed look at all possible mergeable orders, along with past merges and the rules that the merges should follow.