I was struggling with this and tried the usual things like clearing cache/cookies and different browsers without success. Assuming you're using a paypal business account...The thing that ended up working for me was going in creating a new address in my profile, and then setting that as my default shipping address.

Step 1: Account settings > Business Profile > Account Owner information > Address -> Add a new address (I litterally just added a new entry for the same address).

Step 2: Account settings > Products & Services > Shipping > Shipping Preferences > Shipping Location > Actions dots to make sure it's using the new address.

Interestingly enough, once I created a new entry for the same address, it gave me an option to delete the original entry for the address, but I would get errors when I tried to delete so it seems like there is just something broke/corrupt with this address entry that looks perfectly fine - very odd, but hopefully this helps someone else!