It appears the option to "run this query on page load" is only visible when you've selected the "Manual" run behavior. However, a user might not find out about this option if it's hidden entirely.
A solution would be to make it appear disabled instead in case the "Automatic" run behavior is selected. Then, hovering over this option would show a tooltip labeled "This can only be selected if the run behavior is set to 'Manual'", or something along those lines.
I guess the reasoning behind hiding the option might relate to not overwhelming the user with options not relevant to their use case. However, given the context ("Advanced" tab), I would argue users are willing to deal with these options.
Hope this will help users discover the option. It certainly took me a while to find it and the following page didn't quite mention the condition either.