I am not exactly sure what the problem is with some people having issues with fields created in JSON files for options pages.
I just tested this on a site with one of my plugins. The plugin creates an options page and the field group on that options page is loaded from an acf-json folder in the plugin. The field group is not synced into the DB. Everything is working as expected, values are correctly returned using get_field().
There must be some other reason that it’s not working other than options page, json file or syncing.
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