Sorry Elliot, and thank-you for your support, but I’d rather not cross the whole NDA jazz just yet.
If I’m the only one experiencing the problem then I’ll just hold off upgrading.
When I do, I’ll try to do some more debugging to see what is getting saved and how it’s getting pulled out. Clearly something has changed in your api w/acf_get_grouped_posts & acf_get_posts in regards to the PostObject field.
I’ll keep you posted if anything changes.