Bluno Beetle DFR0339 writes only one byte from array

I created an app that writes and reads to the Bluno using Bluetooth. Everything works fine, except when I try to read a byte array from the device I only receive the first byte, while the array has multiple bytes.

I use Serial.write(message); 

Code can be found at https://github.com/Bengkel/Bengkel.Ble.

Any ideas what causes this issue? Is this device specific?