The way I read it, the first dialog showed up the first time you launched the app, and never had the Purchase button. The idea was that 15 days later, you’d see the second dialog (after 15 minutes of recording). Due to the bug, however, the second dialog showed up after 15 minutes of recording from day 1.

The second dialog was always shown (and presumably always had the purchase button), but the difference was between whether users got 15 full free days first or not.