Shelly how change mode (Color/White)

I’m just wondering how to change the mode: color <-> white.
The documentation mentions “Mode” should be available as a channel. But it is not shown on my system (“adanced” is on)
Using OH3.1M4

Another issue is with “gain”. It is not sent to the bulb.
Also “brightness” has values form 0…100 and “gain” from 0.00…1.00. which seems for me inconstistently.

Upgrade to current snaphot. This version did allow me to link my number-item to “gain” and “brightness”. So I realised I had to define it as “Dimmer”
But still no clue how to change between color and white.