I am still not able to recreate this problem. Have you tried deactivating other plugins and switching themes?
I’m not the developer but there’s only a couple of reasons that think of for this happening.
The first is that something is wrong with your installation of ACF.
The second is that there is something that’s modifying the post content for acf field groups. The field group settings are stored as a JSON encoded string in the post content fields.
The third reason is that there is a filter of function somewhere that’s messing with the operator value of the location rule.
