From my experiments with it, it happens predictably when I add layers after i have already created the original set up of included layers previously.
From what i gather, if i add a layer to one camera. that layer will appear in all the camera lists as a layer. but these cameras don’t seem to reliably respect what state you set that new layer to and will only respect the previous state the new layer was set to in the previous camera. My suspicion is that although they appear in the list, they aren’t an “active” member in the list of all the cameras, only the ones you specifically added them to (they behave more like an instance). What i have found is if i use the “copy” function in the layers list of one camera and then paste it in to another camera, even though visually there should be no need to as the layer is there, any edits i now make to the added layer will change properly as i intend rather than just following whatever state it was set to in the previous camera. Like when copying geometry rather than instance.
I am aware how convoluted that all sounds but i hope it makes some sense. Its a difficult thing to describe. Its only a half solution as well as if you had a very complex set of layers switching this could become extremely time consuming and unmanageable if you needed to add a new layer down the line. I try to keep these kinds of setups as simple as I possibly can to avoid complication anyway.