I’m Helen from Shopify Support. Thanks for reaching out about this. Let’s figure out what’s going on here!
In order to know how to proceed, could you please clarify if you are receiving the notification that ‘this item can't be shipped from this location’ from within your admin? Or is this something your customers are seeing while in the checkout? Please share a screenshot of the notification if you can.
Could you also please confirm for me whether or not you have both of the addresses you mentioned are listed in ‘Settings > Locations’? Are both locations set to fulfill online orders? The ‘fulfill online orders from this location’ box should be checked for each location you hold inventory at that will be used to fulfill any orders going through your storefront. It looks like this:
Let me know what you find out!