Amazon GST Issues
You are shipping certain item(s) to a state for which you have not entered GSTIN in your business account. Please note that for such item(s) you will not get GST Invoice. Your business account admin(s) can go to Manage Your GST page and add GSTIN.
Solution Form Amazon Chat
You need to register your gstin in the same state where you are shipping the product. Else you will not get gst invoice if gstin is registered in some other state and product is shipping in some other states.
You are shipping the order in state in which your gstin is not registered, hence you will not get gst returns even if its gst enable product.
The shipping address of your product should be in a state where you have registered your GST for the
same company which is there in amazon account. Means if you have GST registered in Maharashtra then the shipping address should be of Maharashtra.