For this plugin to show all of the accordion items as collapsed when the page first renders you need to make a couple changes to the plugin code. I had the same issue as you guys for about an hour today. Open your plugins directory and then open the accordion-shortcode directory, and then finally open accordion-shortcode.php.
Look for this line, its line 53 in my editor:
$attr['active'] = (int)$attr['active'];
Change it to:
$attr['active'] = (bool)$attr['active'];
Then look for this line, its line 61 in my editor:
'active' => 0,
Change it to:
'active' => false,
Then on your accordion, make sure you set the shortcode to:
[accordions collapsible=true]
This just worked for me, hope it helps.
