deconz-rest-plugin: Scene won't set `ct` for Color temperature light

I have two OSRAM E14 Colour temperature lights (from the time before Philips released their E14 bulbs). I cannot set their colour temperature using a scene.

Here’s the transcript of what I do (using my ph.sh bash script, which is just a wrapper around curl):

$ ph_put /groups/240/action '{"on":true,"bri":254,"ct":370}'
$ ph_put /groups/240/scenes/1/store '{"transitiontime":4}'
$ ph_get /groups/240/scenes/1
{
  "lights": [
    {
      "bri": 254,
      "colormode": "ct",
      "ct": 370,
      "id": "244",
      "on": true,
      "transitiontime": 4
    },
    {
      "bri": 254,
      "id": "241",
      "on": true,
      "transitiontime": 4
    },
    {
      "bri": 254,
      "id": "242",
      "on": true,
      "transitiontime": 4
    },
    {
      "bri": 254,
      "colormode": "ct",
      "ct": 370,
      "id": "243",
      "on": true,
      "transitiontime": 4
    }
  ],
  "name": "default",
  "state": 0
}
$ ph_put /groups/240/action '{"on":true,"bri":1,"ct":250}'
$ ph_put /groups/240/scenes/1/recall
$ ph_get /lights/243/state
{
  "alert": "none",
  "bri": 254,
  "colormode": "ct",
  "ct": 370,
  "on": true,
  "reachable": true
}

The scene seems to contain the correct light states. When recalling the scene, the API reports the issued values (from the scene). However, the OSRAM bulbs actually have a ct value of 153. After having polled the lights, deCONZ reflects this:

$ ph_get /lights/243/state
{
  "alert": "none",
  "bri": 254,
  "colormode": "ct",
  "ct": 153,
  "on": false,
  "reachable": true
}

Oddly this works, when using a similar setup for my Hue extended color lights. I’m not sure if this is caused by the OSRAM bulbs, or whether it’s deCONZ issue with colour temperature lights. It might be related to issue #30 point 3: I see colorloop and xy are specified in the scenes table in the database (my formatting):

[
  {
    "bri": 254,
    "cl": false,
    "clTime": 0,
    "cm": "ct",
    "ct": 370,
    "lid": "244",
    "on": true,
    "tt": 4,
    "x": 30091,
    "y": 26912
  },
  {
    "bri": 254,
    "cm": "none",
    "lid": "241",
    "on": true,
    "tt": 4
  },
  {
    "bri": 254,
    "cm": "none",
    "lid": "242",
    "on": true,
    "tt": 4
  },
  {
    "bri": 254,
    "cl": false,
    "clTime": 0,
    "cm": "ct",
    "ct": 370,
    "lid": "243",
    "on": true,
    "tt": 4,
    "x": 30091,
    "y": 26912
  }
]