Can the lack of fertile cervical mucus prevent fertilization from occurring?

Not entirely. Ideal: ..cervical mucus is clear and elastic (stringy). This type of mucus helps sperm get through the very tiny opening of the cervix into the uterus & then on to the fallopian tube where an ovum can be fertilized. Never underestimate the determination of those little critters, however. Some can & do penetrate the cervix through mucus that's less than ideal. It only takes one! Good luck!