Response from Shopify support suggests that our theme is the issue (they claim to have re-tested on the Debut theme in Chrome on iOS). I’ve attempted to replicate this assertion - replaced our cart page with a fresh copy from Debut & commented out all of our custom scripts. The issue remains: Dynamic checkout buttons display in all browsers except, specially, Chrome on iOS. Bizarre.
Tested in: Chrome on Android (multiple phones), Safari on iOS (iPhone 8-13), FireFox on iOS (iPhone 13), Chrome and Safari on Mac, Chrome on Windows 10 & 11 - all of which worked. However Chrome on iOS continues to display no buttons.
Well, taking their word for it, installed the Debut theme and retested. This is Chrome & Firefox on iOS. Clearly the buttons are not working in Chrome even in their own theme. Anyone else come across this?