First, check to see if Bluetooth is turned on.
Also, Location Services permissions are required for Beacons to function on iOS. Ensure that this is enabled. Check device settings and app permissions to confirm.
Estimote beacons have a "flip to sleep" setting that will make the beacon stop advertising if it is upside down. Make sure the adhesive side is facing down or this setting is turned off.
A document must not be linked to more than one beacon. If you have one document that you want to link to multiple beacons, please create a separate Document entry. Unpublished documents will still be advertised by the beacon.