Why is this script generating "dead spots" in terrain?

Alright, so I was using a Perlin noise terrain script which I got off of the devforum, but for some reason it generates blank areas with no terrain, along the inner corner of an "L" shaped generation. It doesn't clear up whenever you get near, and I haven't been able to figure out what's wrong. Is it something wrong with my settings or the script itself?

local Players = game:GetService("Players")

------------------------------------------------------------------------------------------------------------------------------------------------

local BASE_HEIGHT       = 10                -- The main height factor for the terrain.
local CHUNK_SCALE       = 3             -- The grid scale for terrain generation. Should be kept relatively low if used in real-time.
local RENDER_DISTANCE   = 500 / 4           -- The length/width of chunks in voxels that should be around the player at all times
local X_SCALE           = 150 / 4       -- How much we should strech the X scale of the generation noise
local Z_SCALE           = 150 / 4           -- How much we should strech the Z scale of the generation noise
local GENERATION_SEED   = math.random()     -- Seed for determining the main height map of the terrain.

------------------------------------------------------------------------------------------------------------------------------------------------

local chunks = {}

local function mountLayer(x, heightY, z, material)
    local genstruc = math.random(1,100000)
    local beginY = -BASE_HEIGHT
    local endY = heightY

    local cframe = CFrame.new(x * 4 + 2, (beginY + endY) * 4 / 2, z * 4 + 2)
    local size = Vector3.new(4, (endY - beginY) * 4, 4)

    workspace.Terrain:FillBlock(cframe,size,material)
end

local function chunkExists(chunkX, chunkZ)
    if not chunks[chunkX] then
        chunks[chunkX] = {}
    end
    return chunks[chunkX][chunkZ]
end



function makeChunk(chunkX, chunkZ)
    local rootPosition = Vector3.new(chunkX * CHUNK_SCALE, 0, chunkZ * CHUNK_SCALE)
    chunks[chunkX][chunkZ] = true -- Acknowledge the chunk's existance.
    for x = 0, CHUNK_SCALE - 1 do
        for z = 0, CHUNK_SCALE - 1 do
            local cx = (chunkX * CHUNK_SCALE) + x
            local cz = (chunkZ * CHUNK_SCALE) + z
            local noise = math.noise(GENERATION_SEED, cx / X_SCALE, cz / Z_SCALE)
            local cy = noise * BASE_HEIGHT
            mountLayer(cx, cy, cz, Enum.Material.Ice)
        end
    end
end

function checkSurroundings(location)
    local chunkX, chunkZ = math.floor(location.X / 3 / CHUNK_SCALE), math.floor(location.Z / 3 / CHUNK_SCALE)
    local range = math.max(1, RENDER_DISTANCE / CHUNK_SCALE)
    for x = -range, range do
        for z = -range, range do
            local cx, cz = chunkX + x
            local cz = chunkZ + z
            if not chunkExists(cx, cz) then
                makeChunk(cx, cz)
            end
        end
    end
end

while true do
    for _, player in pairs(Players:GetPlayers()) do
        if player.Character then
            local humanoidRootPart = player.Character:FindFirstChild("HumanoidRootPart")
            if humanoidRootPart then
                checkSurroundings(humanoidRootPart.Position)
            end
        end
    end
    wait(1)
end     

I've tried changing render distance and chunk scale, but I don't really understand most of the math in the generation or how it's scripted. Somewhat of a noob to scripting, but trying to figure things out. Is this generator flawed? and if so, where can I find and or script a better one? Thanks.