Contextual filters exclude option missing I've downloaded the drupalcommerce kickstart but when adding a contextual filter to my view, the "exclude" option is missing.

when I expand the "more" at the bottom the only options are: Allow multiple values and administrative title

do I have to enable the option somewhere before I can access it?

I'm trying to make a list of nodes of the same type, excluding the current node...
The exclude option is a part of the views_handler_argument_numeric handler that comes with views.  If it's not there, it likely means your filter is operating on something other than a numeric argument.  What you have is "Indexed Node: Node ID".  If you create a filter on "Content: Nid" instead then you should see the option.

Also see https://www.drupal.org/node/733686 .