I've been having this same issue and randomly the "some of your lights support adaptive lighting" notification appeared at the top of the Home app on my iPad today. I was able to untick some of my lamps which removed the adaptive lighting from the colour slots on those devices, but foolishly I didn't deselect them all and when I went back to reload the list, the notification vanished.
Apart from the loss of a colour slot, the bigger issue for me is that adaptive lighting overrides any scene I set through the Hue app. On lamps where it is disabled, setting a scene in Hue is reflected on each of the lamps which are included, with correct colour information. Very nice. Where adaptive lighting is enabled this doesn't happen, the colour information is ignored and after 30 seconds HomeKit restores whatever setting it thinks is appropriate. Very bad, particularly when you set a nice low, relaxing level, which is then overridden.
It feels like they just neglected to include the ability to recall the list to enable and disable the feature in the UI elements. I've submitted a bug report which has likely already been filed in the bin.