Why is there still a gray frame after preloading decals?

Here is my script for preloading a bunch of assets:

local ContentProvider = game:GetService("ContentProvider")

local function LoadAssets(AssetList)
	-- Takes an asset list and preloads it. Will not wait for them to load. 
 
	for _, AssetId in pairs(AssetList) do
		ContentProvider:Preload("http://www.roblox.com/asset/?id=" .. AssetId)
	end
end

LoadAssets({306913868,306913878,306913893,306913917,306913938,306913960,306913987,306914028,306914059,306914087,306914112,306914130,306914146,306914168,306914182,306914209,306914230,306914249,306914258,306914271,306914283,306914295,306914310,306914322,306914347,306914366,306914384,306914408,306914444,306914463,306914494,306914547,306914573,306914608,306914634,306914662,306914680,306914686,306914769,306914833,306914872,306914910,306914942,306914987,306915041,306915077,306915117,306915197,306915235,306915267,306915279,306915304,306915344,306915365,306915380,306915404,306915420,306915441,306915458,306915471,306915486,306915500})

local function WaitForAssetsToLoad()
	-- Yields until all requested assets are loaded.
 
	while (ContentProvider.RequestQueueSize > 0) do
		wait()
	end
end

WaitForAssetsToLoad()

Here is what the output is:

https://i.gyazo.com/08e3e14a48ae296e9b7cebec40616ee6.gif

Basically, each decal holds 100 frames, and has a X and Y Size Scale of 10. Then my script changes the X and Y Position Scale accordingly.

You may notice the gray frames when a decal is loading. Preloading helped decrease the decal loading time, but I'm not sure why there is still decal loading time.

All you have to do is put everything in one function, like so:

function loadassets(rQueue)
	cp:Preload("http://www.roblox.com/asset/?id="..rQueue)
	while cp.RequestQueueSize > 0 do
		wait()
	end
end

loadassets(306913868,306913878,306913893,306913917,306913938,306913960,3069139)

That makes your code more efficient and it should hopefully fix your problem.