[BUG] 3-page checkout doesn't work if it contains only bundles

Shopify Apps
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Topic summary

Custom app using Cart Transform API to merge products into bundles causes 3‑page checkout to stall when the cart contains only bundles. Clicking to proceed does nothing and no error is shown.

Address validation UI does not display errors (e.g., missing house number) in this bundles‑only scenario, but validation works if a single non‑bundle product is added to the cart.

Behavior is shop‑specific: the same app works for other clients and on development shops, but fails on this particular store. The developer suspects a conflicting third‑party app, but has not identified one.

Evidence: two linked Loom videos demonstrating the issue are central to understanding the failure.

Another participant reports the same issue and asks for updates.

Status: unresolved. No confirmed root cause, no workaround beyond adding a non‑bundle product, and no official fix reported yet.

Summarized with AI on December 19. AI used: gpt-5.
1

The video explanation

1 more bug video demonstration

Description: we developed a custom app for our client which merges products into bundles using Cart Transform API and faced with a bug if the checkout contains only bundles and we try to proceed to the next step - nothing happens and no errors are shown. The address validation checkout ui also doesn’t work, it doesn’t show error messages on the page if we try to proceed if an address field doesn’t contain a house number but works if we add 1 more NOT bundle product.

We did the same functionalities for all of our clients and it works for them and the same app also works on dev shops but doesn’t work on this shop.

The only 1 possible reason, as we guess - some application which breaks the checkout if it contains only bundles but we can’t find such app

2

Hi,

We are experiencing the same issue. Is there any news about it?

Regards,