Sound like a
Struck Through Grease issue. When the dies devices get filled with grease the grease can prevent a device/devices to be filled with grease. These only have a premium when most of the devices are missing. Otherwise it is just a grease filled example.

Common to see a few devices affected, but the 80% fill are the collectables:

So the lesser ones are considered normal. But that is what prevents the strike of those devices.