I am not too familiar with the rainfall maps for Oahu, so not sure how much rainfall you get. I thought all of Honolulu was relatively dry. However, the current El Nino conditions have moved the rain around, so perhaps you're getting more rain than usual. The symptoms you describe are consistent with disease, anthracnose being the biggest culprit. Florigon is supposed to be moderately resistant, perhaps it's not as resistant as advertized. Here on the North Shore of Kaua'i where it rains a lot, I stick with the bulletproof disease resistant cultivars. Nam doc for example may be a better choice for you.

You know what they say about planting new trees:

The first year, they sleep, the second year they creep, the third year they leap.