If you experience lag, there might be a delay before the search screen appears. If, during this time, you drop another bomb/probe, the first session will automatically be canceled and you will lose that search.
Sometimes resources are inaccessible. They might be stuck under trees, stones, turrets or buildings or they can be located on steep slopes which your avatar cannot climb.
You can extract the claim by choosing to summon it by right-clicking on the deed and selecting "Summon claim". Please keep in mind that your movement will be locked while the claim is being summoned.