You mention the add new storage location - but what exactly are you trying to add? Your message is pretty vague and I'd like to make sure that I don't send you down the wrong path.
I think I am running into the same issue as this person. I have added part items to the listings, they have part numbers as well. I cannot though add to the inventory without selecting a location. The drop down menu has nothing in it and it prompt stating it's a requirement for the part location. I do have locations filed inside of our asset system so I don't understand why they don't show in the portion. Here is a screenshot.