Why didn't the onychomycosis after 1 cycle of sporanox (itraconazole) didn't go away?

May not be effective. Assuming you do indeed have onychomycosis, the medication works on the new nail growing in. So you typically don;t start seeing any difference for about 3 months. Even after you complete a full course of medication not all medicines are 100% effective.
Too soon to tell. Even if it is wildly successful, it takes several months with sporanox (or Lamisil (terbinafine) oral or even laser therapy) to see results. It is because nails grow so slowly and the new nail--the back of the nail--will hopefully be clear, but it takes several months for the new nail to become visible. If working, the nail will grow in like a window shade with progressively more of the nail being clear.
Not a fungus? Your onychomycosis should have been verified with fungal culture which should include a pas stain to avoid false negative culture results. Sporonox is typically taken over 3 months but does not have a 100% cure rate. Other oral antifungals include lamisil (terbinafine). Other conditions can cause a thick nail and you should be positive that it truly is a fungal infection.