Cannot discover attributes

Hi,
Working with CurieBLE (version 2.0.0) on my Intel Curie Nano Board (version 2.0.2), I'm trying to use SensortagButton from "CurieBLE->Central" samples on Arduino IDE 1.8.5.
I managed to scan my device, print advertised service, connect, but when it comes to discover attributes it fails.

```
Discovered a peripheral
Address: F5:E2:ED:45:19:33
Service UUID's: d5060001-a904-deb9-4748-2c7f4a124842
RSSI: -69
Device connected
Attribute discovery failed!
Device disconnected
```

In rare cases, discoverAttributes() returns true, but no service is found, no characteristic either.
Curiously, i manage to list every services and characteristics using a BLE Scanner app on my android phone.

Any clue ?

Start with the CurieBLE->Central SensortagButton sample and the discoverAttributes() call, using the reported CurieBLE, board, and Arduino IDE versions as the reproduction context. Compare the failed and rare empty discovery results with the Android scanner; done means attribute discovery succeeds and services and characteristics are listed.

Written by the indexing model from the issue text.