Newby - Filament runout! error, No sensor.

Hi, New to 3D printing here.
I bought an Ender-5 Pro off Marketplace with a Bigtreetech screen running Marlin bugfix 2.0

However, on my 1st print I received a filament runout error.
As far as I can see there is no filament runout sensor on the Ender-5 Pro, just the extruder on the rear right upright that feeds the filament from the roll to the blue tube.
Am I missing something or is there a software mismatch?
Thanks for any help for a noobie.
Reyn - Australia.