If you are using a Custom Post as your front page then when the responsive theme updates, it defaults back to using its own home page, so whenever you update the theme check the theme’s appearance under HOME layout and see if it is checked as the home page to use and then uncheck it.
You can always look and verify after updating.
Under the “Home Page” section at the top of the list you will see a check mark box, for making the responsive home page layout your website home page. Again, it should Not be checked.
This is a quick fix to allow you to use your custom page or post as your front page. To use the defaulted resposive theme layout then just simply check the box and fill in the required information.