GetFormsInfo doesn't return all forms

We run a scheduled task (running from episerver) that loops through all available forms in our episerver instance and exports any submissions that have been made since the last time the scheduled task was run (every 24 hours).

To get the the available forms we run

var formsInfo = _formRepository.GetFormsInfo(null);

foreach (var formInfo in formsInfo)
{

// check if the form has data, do something with data

}

where _formRepository is an instance of EPiServer.Forms.Core.IFormRepository.

Recently a user has created a form that does not get picked up by the GetFormsInfo method.

What (if anything) stops a form being picked up by this method?