thanks
There doesn’t seem to be anything relevant in debug.log, tons of errors but they occur exactly the same even when the bug doesn’t, relating to sidebars, etc… will send a copy anyway as private. I know errors aren’t great but they don’t appear to be linked to this issue.
Have worked out that the bug only shows when ordering for the 1st time, or after clearing browser cache/cookies etc, so it’s easier to test on a new browser each time I’ve just got it to happen on Chrome, Edge and Safari. Each time, after clearing the order and going back through the process it never experiences the bug again till cache is cleared.