Mueller Tint remote, oblong button

Hi all,
I’m using hue essentials to control one smart bulb and two smart switches. I also have a Mueller Tint remote which can be set up in the app. I can assign functions to all the buttons which works well. The only thing I cannot do is assign something to the lowest oblong button, the group chooser in the original configuration. In the image in the app, the button cannot be activated like the others.
Is this functionality not yet implemented?
Thank you,

I assume you are using deCONZ to configure your Tint remote.

Unfortunately, I have not found a way yet to configure the Groups button at the bottom or detect which group is selected. There is some information in this comment: