When you create a custom page that is located on www.example.com and your board is inside www.example.com/community/, viewonline will display users on the custom page as if they were on the index page of the board.

The problem is this preg_match function in viewonline.php:

	preg_match('#^([a-z0-9/_-]+)#i', $row['session_page'], $on_page);

If the saved session_page looks like ../test.php, this preg_match will just remove the session_page and the $on_page will be set as empty array.
For the time being I just changed the if statement directly afterwards from this:

	if (!sizeof($on_page))

	{

		$on_page[1] = '';

	}

To this:

	if (!sizeof($on_page))

	{

		// if user is on a page like ../example.php, show that

		if(substr($row['session_page'],0,3) == '../')

		{

			$ext_spot = strrpos($row['session_page'], '.');

			$on_page[1] = substr($row['session_page'], 0, $ext_spot);

		}

		else

		{

			$on_page[1] = '';

		}

	}

But that is just a mean fix to me. It's probably best to change the preg_match regex.