Thanks Elliot. Yes, that works well. I had that going at first but ran into some other wall that got me to look at the docs and try the setup_postdata()
route.
I’ll mark this as solved and file it mentally under ‘setup_postdata function can cause many problems with the global $post object.‘ I’m having other problems on the page now with conditionals and sub_field values which I’ll chalk up to that too! Will retry your suggested method.