Puck.js with Node-RED on Raspberry Pi

Retrieving sensor data works flawlessly.

d1:46:17:ce:38:85 - Puck.JS WZ (RSSI -59)
  1809 => {"temp":19}
  180f => {"battery":100}
de:87:72:1f:9c:41 - Puck.JS BK (RSSI -73)
  1809 => {"temp":8}
  180f => {"battery":100}

However, transmitting commands always fails:

MQTT>/ble/write/d1:46:17:ce:38:85/nus/nus_tx => "digitalPulse(LED1, 1, 100);\n"
Service         6e400001b5a3f393e0a9e50e24dcca9e
Characteristic  6e400002b5a3f393e0a9e50e24dcca9e
<Connect> Error Connecting

Does any one know what could cause this issue?