LIGHT GROUPS don't work as expected vs. A GROUP of LIGHTS - bug?

I’m trying to convert some groups of lights (ie: LIGHTS in a GROUP) to a LIGHT GROUP.

It seems that Light Groups do some weird things compared to individual lights or groups of lights when controlled by google assistant.

I have 2 LIFX bulbs configured as “couch_1” and “couch_2”
I have also made a group called “couch lights” containing “couch_1” and “couch_2”
I have also made a Light Group called “Sofa lights” containing “couch_1” and “couch_2”

let’s say I set the two bulbs to green, 20% brightness

if I ask google assistant to set the individual lights or the group “couch lights” to blue, they transition over about 1 second to blue, and stay at 20% brightness

if I ask google assistant to set the LIGHT GROUP “sofa lights” to blue, they instantly change to blue, and also go to 100% brightness

I can set a light_profiles.csv file to make a default transition time of 1 second to fix the abrupt change when commanding the Light Group, but not sure how to fix the change to 100% brightness. I would have thought a light group would have worked the same as a group of lights in this regard?

is this a bug? am I doing something stupid?