Unfortunately I haven’t had a chance to revisit the issue. This was on a client’s live site, and I couldn’t really justify either tinkering with their live site now that it’s working, or being “on the clock” to set up a test copy of their site just for the sake of experimenting with it.
Are you referring to the “Core: Fixed bug where updating value did not clear persistent cache” change in version 5.3.9? My client’s site was running the latest version of ACF when I posted my original reply on August 19, and 5.3.9 was released in June, so that wouldn’t have been a factor. That is the most recent note in the change log pertaining to caching.
