As @David said, if you used the Eddystone URL, the register option in the beacon tools will be grayed out.
But just turning on Eddystone UID will not work for me, because the beacon tools will not recognize my beacon at all. What I did for this work was to include the iBeacon and Eddystone UID during configuration.
After you register the lighthouse on the lighthouses, you need to update the "registered" list to see it there. Or go to the Google developer toolbar of your project.
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