8.5.2 is live for ACF PRO, but it looks like the fix hasn’t been released for the free version yet.
As a heads up for anyone having this issue, it’s been fixed in version 5.8.2.
Thanks to everyone who posted here so we could narrow down the issue. While modifying the database directly does fix the problem, that presents a significant amount of risk and also would be incredibly time consuming if you’re managing a lot of websites.
Does anyone know if the ACF team is working on rolling out an official fix for this?