How to cite Kindle books/ebooks when no fixed page numbers are available?
According to the APA blog, the location number is actually a bad idea because it has limited retrievability. The blog also mentions that since Kindle's third generation, e-books have started to have real page numbers, you may try looking into that.

Another post on apastyle.org suggests that for materials that are not paginated, consider citing chapter number or chapter heading plus paragraph numbers.