No so essentially the theme is creating the inline moderation problem.
I have fixed the root issue as inline moderation works perfectly fine using the default theme however once I switch to iGame by iAndrew, I am given the same error that I displayed in the original post.
If that makes sense at all
Okay, you'll need to apply the headerinclude change again. The theme will use a different template set to the default theme, and comes with an older version of the template (as the theme's not been updated for 1.8.9 yet).
So, if you go to ACP > Templates & Style > Templates, you should see a template set for each theme (they should be named accordingly). If you go into this template set, and go down to the Ungrouped Templates, edit the headerinclude, and after:
var cookiePrefix = "{$mybb->settings['cookieprefix']}";
will need:
var cookieSecureFlag = "{$mybb->settings['cookiesecureflag']}";
This will probably be an issue with most themes, as like I say they will come with older versions of templates, without the changes made in 1.8.9, so they just need to be manually applied until the theme is updated.
I love you!
*not gay btw xD*
Your code works - can't thank you enough! Once again myBB support saved the day!