How is this even a problem? I have spent hours and hours setting up my store and getting it live to lose my first customer due to shipping costs stacking. Basically, they ordered two products, one was £2 postage, one was £3 postage. The postage got combined to £5 due to the 2 profiles. Of course the SENSIBLE and LOGICAL thing is to offer a simple checkbox which only charged for the greater postage. (1 or 2 lines of code).
this is a known issue that many of people do not have a solution for. Why has this not been addressed?
Ps. please dont come here and link your $29 per month third party app to fix this ridiculous restriction.
When using multiple shipping profiles, if orders contain products from different profiles or locations, this will result in combined rates at the checkout. At this time, there is no way to disable combined rates natively if you have multiple shipping profiles, or have multiple locations within profiles. I understand how frustrating it might be, being unable to handle this within Shopify.
Ultimately this feature is in place to ensure merchants don't end up over paying for shipping when customers order products from multiple profiles or locations. Currently the only available work-around would be to use an application to set up more specific shipping rules.