Unfortunately, Facebook only hosts lead information for 30 days after a campaign. After this time, we lose access to the campaign demographic and viewing data that was once on your status page.
However, if you only want a list of leads for the campaign, you can visit your order details page from the ‘Orders’ section of the TriggerMarketing app and download them as a .csv from there.
To avoid issues like this, make sure you're viewing your status pages when we email you from email@example.com so you can download your leads via a .csv format from these pages.
You can also try following Facebook’s Help Center steps to retrieve leads from your account (here).