The attribute 'root.translateX' is locked or connected and cannot be modified?

I need some help.
I just edited an existing character with the animation & rigging tool.
So now I wanted to publish it but when I click on “build” and make a snapshot I only get the message:

Error: RuntimeError: file C:/Program Files/Epic Games/4.8/Engine/Extras/Maya_AnimationRiggingTools/MayaTools/General/Scripts\ART_skeletonBuilder_UI.py line 6679: setAttr: The attribute ‘root.translateX’ is locked or connected and cannot be modified.

How do I unlock or disconnect this or what does that mean exactly? I cant find it anywhere …
I hope someone has any ideas?!
Thanks a lot!

In the Maya Preferences / Settings / Animation you can find Animation Blending. If it is set to Never blend then it prevents setting or keying any already driven attributes.

Try to set it to Always blend, building should work then.