the Enable and Disable checkbox column has disappeared..

Hello everyone,

I have noticed that the Enable and Disable checkbox column has disappeared from the rules window.
I have tried the following:

- I went to Preferences > Security but the Prevent Rules Editing option is not listed. There is no trace of it.

- I selected an unlocked rule and then went on Edit > to select Enable or Disable but both options are greyed out (not selectable).

Any ideas of what the problem could be?

Many Thanks