Hello,
I do not know what the problem might be with so little information.
If this is a freely available theme, simply point me to it and I will test it.
Otherwise I would start by looking at the usual places: JavaScript console, WordPress debug log, PHP error log.
There should be an XHR request from the frontend to your server doing a get_user_info call on the JSON API. Can you see this request in your browser’s network console?