I am having the same issue! I want to offer a flat rate shipping but I have multiple locations which is charging double of the price if a customer adds products from different locations and triple if he/she adds 3 products from 3 different locations - this is ABSOLUTELY UNBELIEVABLE!
Did someone find an answer? Please advice!
I've been experiencing the same issue with doubled shipping and found this thread. Yet another confirmation (5th this year) that it's time to ditch Shopify for good and find an alternative
I seemed to have fixed it for my store, but this solution might not work for everyone. We have 3 locations setup, but I removed the shipping rates for 2 of them and now only have shipping rates for 1 location, I have tested to see if a product is only in stock in a location without the shipping rates then it still allows the purchase to happen and it only charges the one shipping rate. I hope this helps other people!
I think I figured out one fix that works after a couple chats with Shopify support. The first person I talked to was completely unhelpful (extensive solutions were given to problems other than the one I was experiencing). I tried again and got somebody who seemed determined to figure out a fix, but at first was unable to find a solution other than to suggest shipping apps. She then got back to me later and offered this advice:
We can push this manually through the product editor:
Choose your product you would like to change inventory management for
Scroll to the inventory settings
She provided this link as an example:
I tested this on a few products and it seems to be working. I am getting the intended shipping rate rather than a doubled rate. The issue still is that this must be changed for each size of each variant for each product, so it is incredibly tedious. It really should not be this difficult, but at least it seems for the time being that this fix will work.