Why is the list I imported into the CRM campaign not showing in my filters?

After importing leads into Vtiger CRM, the records will appear in the Leads module, but they will not automatically show in filters. To make them available:

1. Log in to the CRM. 
2. Go to Essentials > Leads module.
3. Create a filter by setting conditions that match your imported leads (for example, Source = Import)

Now, all the imported Leads will be shown in the new filter added.