If you notice that your "Next" button and order summary are missing when viewing your store on a mobile device, don't worry—they're not actually gone. Most likely, they're being blocked by the Shopify navigation menu you set up.
Here's how you can fix it:
Hide the Shopify Navigation Menu: We can help hide the navigation menu, but it's not recommended as it could cause other issues.
Disable the Shopify Navigation Menu:
Go to your theme settings.
Find the "mobile sticky bar" settings.
Disable the Show sticky bar option.
Keep in mind that disabling the navigation menu will affect all parts of your website, not just the Bundle Builder page.