Fadedown with RGBW bulbs not working correctly

[CoolSaet]

I have RGBW bulbs setup with 4 different groups. When I use the fade down command on a specific group, that group is turned off immediately and the others are faded. When I fade down all groups, all are turned off immediately.

With the fade up command It seems to work OK, except that before fading up, the lights are turned to full brightness for a split second.