Cortana still insists on using the wrong address, but if I don't select my location in the map app after I boot up, she uses a completely incorrect location.
Pretty much all the Windows applications sync their data to the cloud which is why you have to use a Microsoft account. Cortana may not be updating the address in the cloud.
I have sync turned off. When I first used the Map App, a message popped up asking if I would allow "Maps" to access my location. I agreed to this. Since then , if ever I choose to open it, my location is there.
I should add, if it is significant, I do not use Cortana.
I do like having her on my Windows phone because I have to find where people want to meet up but on my desktop machines she is just a cpu/ram hog I don't need.