Why wont WorldRoot:Raycast work sometimes?

I made a tool that casts a ray to the position of Mouse.Hit.p, and a beam would appear between the tool's handle and RaycastResult.Position. However sometimes the ray doesn't seem to hit anything at all so the beam doesn't appear. I know for sure that this is is a problem with raycasting and not the beam since WorldRoot:Raycast wont return anything.

-- Only important parts:
local function fireLaser(player, MousePosition)
	local origin = LaserPart.Position
	local params = RaycastParams.new()
	params.FilterDescendantsInstances = GetParamsList:Invoke(player)
	params.FilterType = Enum.RaycastFilterType.Blacklist
	
	local rayCast = game.Workspace:Raycast(origin, (MousePosition - origin).Unit, params)
	
	if not rayCast then
		return
	end
	
	local aPart = AttachmentPart:Clone()
	aPart.Script.Disabled = false
	aPart.Position = rayCast.Position
	aPart.Parent = game.Workspace
	Beam.Attachment1 = aPart.Attachment
end

I also made a turret that tracks (p1.CFrame = CFrame.new(p1.Pos, p2.Pos)) the first player that it sees, and the same problem occurs.

-- Only important parts:
local params = RaycastParams.new()
local FDI = script.Parent:GetChildren()
for k, v in pairs(TurretPart:GetChildren()) do
	table.insert(FDI, v)
end
params.FilterType = Enum.RaycastFilterType.Blacklist
params.FilterDescendantsInstances = FDI

while true do
	-- ...
	wait(1)
	hit = game.Workspace:Raycast(TurretPart.Position, (hrp.Position - 	TurretPart.Position).Unit * BulletSpeed, params)
end

Also, there's a Ray object separate from WorldRoot:Raycast, but I don't know how to use it.

if a ray doesn't hit anything, WorldRoot:Raycast will return nil

the old raycasting api did return the position where the ray would have ended, but the old api has been deprecated for a while now, so you shouldn't use it

you can find the position where the ray would have ended by just doing origin + direction

local dir = (MousePosition - origin).Unit
local rayCast = game.Workspace:Raycast(origin, dir, params)

local aPart = AttachmentPart:Clone()
aPart.Script.Disabled = false
aPart.Position = rayCast and rayCast.Position or origin + dir -- this almost works like an if statement, it's like doing if condition then a, else b
-- they're not exactly the same though
aPart.Parent = game.Workspace
Beam.Attachment1 = aPart.Attachment