Fading not working for innr lamp


I have an innr RB 285 C in a group with Hue lamps.

The fading is set to 1 sec and works nicely for the hue lamps, but not at all for the innr lamp. It just switches at the end of the fading time to the next setting.

Interestingly, it worked really well with the Hue bridge with the same lamps.

Is there a setting I have missed?