Switch Statistics only shows data for ports with clients that are currently powered up.
I was trying to view some statistical information on a device that is connected to Port 3 on my switch.
Because the device wasn't powered on at the time I wanted to view the data I couldn't view any data on this port.
Per the screenshot below, I am trying to view data for the last 30 days for all ports on my switch (except port 7 which is disabled) and as you can see below there is no data showing for Port 3 and Port 5. These ports have devices connected and that are in use regularly but were powered down at the time I wanted to look at this data :