Checkout Extensibility: One-page mobile interface not displaying order summary

Shopify Plus

Topic summary

  • Issue: On mobile, the checkout customizer preview shows an order summary dropdown at the top and a summary at the bottom, but on actual devices (Safari and Chrome) the top summary is missing.
  • Context: Shopify Plus store using the Dawn theme with Checkout Extensibility and the one-page layout (consolidates checkout steps onto a single page).
  • Peer feedback: Another user confirms seeing the order summary in both preview and live versions; shared screenshots. Images are central to illustrating the expected behavior.
  • Troubleshooting questions: Asked to verify that the live checkout is truly set to one-page and whether visual edits (e.g., colors) appear on the live checkout, implying a potential mismatch between preview and published settings or device/caching differences.
  • Status: Unresolved; awaiting confirmation of layout settings and whether changes propagate to the live checkout.
Summarized with AI on January 8. AI used: gpt-5.
1

I’ve updated to checkout extensibilty for a shopify plus (dawn theme) and am trying out the one page layout.

In the checkout customizer preview for mobile, it shows an order summary drop down at the top of the screen. There is also an order summary at the bottom of the one-page layout.

However, when I view checkout on my devices in safari and chrome - there is no order summary at the top.

Is there a setting I’m missing somewhere to diplsay the order summary at the top of the page?

2

Hi @kmdesign ,

It strange, like you can see below, I’ve got the order summary in both version.

ClementOutis_0-1705402302818.png
ClementOutis_0-1705402302818.png688×774 79.7 KB

ClementOutis_1-1705402323280.png
ClementOutis_1-1705402323280.png719×767 298 KB

Does the checkout that you view (not in preview) is in one page?
If you made an edit (like colors or somethings), does it affect the checkout you viewing in chrome or safari?