Atmega32u4 not detected
18pF capacitors will cause the crystal to oscillate at slightly lower frequency, but shouldn't stop it from working. To check that it is oscillating you need a high impedance probe (eg. oscilloscope probe on x10 position) connected to pin 16 of the ATmega. You should see a sine wave with peak-to-peak amplitude of at least 2V.

If you just see a DC level of around 1~2V then the crystal is not oscillating, either because it is faulty or not connected. Are you sure that you have it orientated correctly?