Could you please share the JSON export file of your field group and the screenshot of the issue?
Also, could you please share the steps to reproduce the issue so I can test it on my installation?
Another thing I want you to test is to try to reproduce the issue on one of the WordPress’ stock themes (like Twenty Sixteen) with other plugins deactivated. If it disappears, then you can activate the theme and plugins one by one to see which one causes the issue. This will make sure that the error is not caused by the conflict between ACF and your plugins or theme.
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