Light Levels do not seem to be corect in Villager Farm

I was working in Pre release for 1.13 Pre 2, I was testing an Automatic Potato Farm that uses Light Level 7 on one block to function. But when I check the Light levels in the build they all read as 0 Sky 0. the Farm is 15x15 with Glowstone at each corner and in the middle of the Edges as well as 4 in the middle 4 blocks above and one in the center at 7 above with an opaic block below it 4 blocks above the dirt.