Touched event not firing when a player is standing still in a size changing part after Release Note 662

At February 27, 5:22pm, 30 minutes after the release notes for 662, I noticed the .Touched event is not firing properly when a player is standing still in a size changing part. This has affected all of my parts and models that rely on .Touched event to damage players, such as lava bricks.

Reproduction Steps

  1. Create an anchored part, I used a thin cylinder part placed slightly above the ground
  2. Use a script to continuously change the size of the part, I used the script below
local TweenService = game:GetService("TweenService")

script.Parent.Touched:Connect(function(hit)
	if hit.Parent:FindFirstChild("Humanoid") then
		hit.Parent.Humanoid.Health -= 1
	end
end)

while true do
	local TweenInformation = TweenInfo.new(5,Enum.EasingStyle.Linear,Enum.EasingDirection.In)
	local TweenGoal = {Size = Vector3.new(0.55, 22, 22)}
	local TweenGo = TweenService:Create(script.Parent,TweenInformation,TweenGoal)
	TweenGo:Play()
	task.wait(6)
	local TweenInformation = TweenInfo.new(5,Enum.EasingStyle.Linear,Enum.EasingDirection.In)
	local TweenGoal = {Size = Vector3.new(0.55, 5,5)}
	local TweenGo = TweenService:Create(script.Parent,TweenInformation,TweenGoal)
	TweenGo:Play()
	task.wait(6)
end
  1. Stand within the part where your character is always touching the part, I stood close to the middle for my example below

    As you can see in the video above, I am not taking any damage despite the part changing in size, this was not the case before. Even parts of my character such as left hand is not triggering the .Touched event despite the red damage part moving away and back towards it.

Why this was NOT something I did to my game

Note: I have not been on roblox studio at all today and I have not updated any of my roblox games so It couldn’t have been because of me. I have also tested this in a baseplate game and the issue still occurs. This also just happens to be the same time as the release notes for 662 so this is my best assumption as to where the issue has risen from.

Why this is important to me

This is very important to me as it changes how players interact with parts in the world, this bug can now allow players to stand still and not take any damage, I would really appreciate if this could be fixed.

How I initially discovered this issue

I created an Anti-Cheat System which used a giant invisible part to check if players can trigger .Touched Events. At 5:22pm (30 minutes after release note 662) I started getting flooded with reports, saying most players are “cheating” due to not being able to fire the .Touched event when touching this invisible part. There are also some cases where players moving towards the invisible part fail to trigger .Touched event.

Expected behavior

I expect that the .Touched Event will continuously fire as the shape of the part changes, this has always been the case before and I depend on this for basically everything I do relating to Touched events.

Mockup example of previous behavior

To be fair, the documentation says it fires only after “physical movement”, which isn’t even enough to say if this was intended behavior or a bug. I think that should be updated as well to be less vague.

1 Like

While that is true I do not believe it was mentioned anywhere about the behavior of Touched being updated or fixed.

The Touched event is one of the most basic core features that most people use, I would highly expect some sort of warning before a change like this.

2 Likes

Here is another example where .Touched refuses to even work (this was the invisible giant part from my anti-cheat I mentioned in the main post)


The only time I take damage is if I stand directly in the center of the part and move around at the same time

Reached out to the dev in a private message to further investigate.

2 Likes

Docs are right, pretty sure this isn’t a bug. This has happened to me before.

Whether or not the docs are right, something has recently changed with the behavior without any warnings and that’s what Im reporting, I’m currently waiting to get home so I can test further.

2 Likes

We’ve released a fix for the issue and the problem has been solved. Thanks again for reporting the issue!

1 Like

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