Here is a guide on how to open your stacked boxes since you cant get the full reward opening them all at once.

First you have to join our discord and find our addon channel

Then click the link and it will transfer you to the google drive 

Fund the enchanced stack Split and click on the 3 dots at the end of that row as shown on the picture.

Once you have the zip file downloaded open it with winrar or 7zip doesn't matter and upack it in your wow/interface/addons folder or on your desktop

in my case is in drive D but you must place it in your game folder addons.

Once placed there you should be able to find the addon folder inside the addons fodler

Once that is done open your game and unstack your boxes by holding shift and right clicking the stack you want to unstack.