Thanks for your prompt answer.
Regarding your questions:
1) I'm using the Android Estimote SDK to build my own app.
2) I don't know if they are D3.X. All I know is that the firmware version is 4.9.4 and the hardware version is G1.8. (for all beacons)
I followed the link you sent me. I updated the Estimote SDK to 1.0.3, as it says. But, unfortunately, the problem remains.
As I told before, I'm able to find the beacon, but when I try to get its info from EstimoteCloud, I get that 404 error.
Should I follow any other procedure?