The tech loader will (still) show you a list of missing blocks, but it's hidden away inside some optional menus, at the bottom. You're far from being the first to have difficulty finding this. Probably could do with a design tweak.
Note that the numbers shown inside the cell of each missing block is the *total* number used in the tech, not the number missing. You have to select each missing block to see how many more you need after using the ones in inventory.