T3 Won't Save

I have an annoying error that means my t3 template won't save any changes, such as layouts, name change, features on and off; anything at all. When I click save, I get this error in the inspector:

[Error] TypeError: 'undefined' is not an object (evaluating 'vis.vals')

I have updated Joomla and am running the latest of everything, and have searched the net only to find other people with the same problem, and no solutions being offered. There's even a thread on this forum without any solutions.

http://t3-framework.org/discussions/problem-in-admin-javascript-error-vis-is-not-defined-when-saving-the-template.html

Any help available?

Many thanks