If you look closely enough, which you evidently must have, neither centre tank low pressure light is lit meaning there is still fuel in the tank and both pumps are working.
The centre tank gauge, especially on the 3/4/500, can often read zero when there is still fuel in there and as such the master caution won't come on until BOTH low pressure lights are lit. This is really the only way to tell that the tank is actually empty.
I don't know whether to say 10/10 for observation or you need to get out a bit more! :
