In the main pane (in Details view) at the top there is a horizontal list saying stuff like Name, Type, Modified etc. Right click on any one of these and it brings up a list. Check to see that "size" is checked or not. If "size" isnt on that list, click on the "more" that appears at the bottom of the list and select it.
HTH
Oggin
P.S. BTW It isnt size that matters, its what you do with it that counts
P.P.S. And that isnt another sea farer's thing Beagle !!!!!