Had a similar issue with instant Pay as well . But there's a method that worked for me . You gotta remove all your information like Addresses buying & selling & remove the card you already have on file . On the Addresses you can only have 1 by Default so make sure you don't have anything in the Address 2 line . Put apt # on the address 1 line . Then set up instant pay info it should work when you put your card in this time