Hi @geoff-grav,
I just started working the forums so hopefully you won’t have to go on a bump-frenzy anymore. We’re now a few people that will support you guys.
I’m not sure wether this should fall on ACF or WP Core. Triggering revisions saving in an edit-post screen is done by WP Core and it would seem it does not react to the creation of new input fields (not so strange).
I’m not sure there’s a possibility to even trigger revisions manually? That’d be a necessity if ACF would take a stab at it.
Have you tried this plugin? I haven’t looked at it closely but perhaps it does what you want: https://github.com/adamsilverstein/wp-post-meta-revisions
