CAT rig and spring controller setup

Hi,

so I´m back with CAT rigging for my new employer…and back to the weird quirks it comes with…

I´m going to rig a chameleon and I´m trying to find out how to do all the stuff I wanna be able to do with it, that doesn´t come premade with CAT…

First thing I did: create custom stretchy bone chain using this script:

http://joleanes.com/scripts_plugins/chaintools.php

Then I created 3 extra CAT bones on the Jaw bone and aligned them with the helpers for the Spline IK.
Then I linked the Helpers to the Extra CAT bones:
This way I can animate the custom bone chain using the Extra Cat bones as Control objects and profiting from the layer animation system.

Then I went even further and added a spring controller to one of the Extra Cat bones for that extra bit of spicey secondary motion…
This is where it got weird:
To add the spring controller, I ticked “animation controller” (hierarchy->Link Info).
I also ticked “additive to setup pose” on that bone.
But as soon as I add the spring controller, the bone snaps to another position.
I tried to fix this manually by adding an absolute layer and positioning the bone back to its original position.
That seemed to work and I did a test animation on that layer, but today, as I loaded the project back up, the bone had snapped to an even weirder position.

Any idea what I´m missing?

I´ve attached a picture of the setup: