This is DEFINITELY a privacy rule issue. Instead of enabling all fields in the privacy settings, I’d recommend you delete you privacy rules (on the user data type) one by one and keep refreshing the preview page.
You should be able to see all results as soon as you delete the culprit privacy rule. Once the culprit is identified, just press undo till you’ve got all your privacy rules back.
Now just fix the broken rule(s) and you’re good to go 