I know this is an old thread, but as far as I can tell, the issue is yet to be addressed.
I’d actually be very happy if the metaboxes just stayed collapsed once you collapse them, the way WP’s standard metaboxes work.
Currently if I collapse an ACF metabox and leave the edit screen, then come back to it (or open a new page that contains the same ACF metabox), the metaboxes are open again. Also, if you collapse them, then update the page, they are reopened.
