Here is the actual solution, it's not ideal but it works as I did it after waiting years for QBO to fix this issue.  Unfortunately it adds more inventory items, but I only have 1,000 to begin with so it grew to 5,000 for my 5 locations.  Add a prefix with the initial of each location before the item name.  So for me I added H-, M-, C-, etc in front of my excel imports (there's an excel formula to do this quickly).  If you have 2 locations starting with the same letter you'd have to go with 2 letters.  So for my inventory items my staff know now to enter H- when searching for their own stock in Hinton to add to an invoice.  As you type H- now you're looking at all of your Hinton location inventory and for example I have 1/2" mild steel plate which is PL 1/2 so they type H-PL and then they're looking at all of their plate in inventory.  As a further note to save you some trouble on importing, it won't let you import 0 quantity items so I simply put a very impossible quantity you'd ever track of 0.0001 so I know any items with that quantity are actually 0 and I don't have to painfully add them later.