Can't update firmware

I have a developer kit of beacons, they are working and I can see them on the app.

When I try to use the Deployment app to update the attachments of the beacon and also to update the firmware of it, is not working. The deployment app shows 0 beacons in range to be updated and if I select the “Update firmware” option it shows me 3 beacons in range to be updated. If i try to update the 3 beacons, all of them fail.