Yes it’s kind of an “issue” if you want to call it like that. Here’s what I’ve been doing: Clear all the area or the zombies will attack you while carrying the box and you can possible die. After you have cleared all the area pick the box and take it to the cutting machine and drop some copies before using that. Once you have placed the box it starts to remove the lock. Open it and enjoy the goods. Take what you need to your base return to the farm and this is very important!! Take all the remaining stuff from the box you just removed the lock and then you can pick one of the copies you dropped before and repeat the whole process and keep collecting nice stuff ???
This have worked great for me. Hope it helps guys!