Looks like an incorrect setting for overprinting the blue. Overprint/Overlap gives you three choices: None, Overlap and Overprint. If None is your choice then the blue will knock out the white taking a little extra around each shape. If it's Overlap, then the blue will print totally over the white which is ok in this scenario because there's no color shifting going to happen. If it was blue on yellow, for example, then the overprinted areas would shift towards green. If you are overprinting two colors that will color shift, then you will get better results using the Choke and Spread feature in Composer.
Finally, Overprint does exactly what Overlap does except that it also turns up the temperature on the printhead ...which may be beneficial with large overprint areas but will also result in the need for two print passes for the blue in any other instances of the blue that do not also have Overprint as the setting because a different printhead temperature would be needed for each pass effectively doubling your cost to print the blue.
Try selecting the blue shapes in Composer and enter Control + the F5 function key to turn on OverLap and see if it prints correctly.