Child actor component and Template bug

Hello ,

I was unable to reproduce this issue on our end I have a couple of questions about your issue to help me narrow down the issue you are experiencing.

  1. Can you reproduce this issue in a new project?
  2. If so, could you provide a detailed list of steps so that I can reproduce this issue on our end?


yes i can reproduce this here is step by step how to do it and the project zip if needed

1- Launch unreal engine 4.17.0

2- Create a new project based on this settings (Blueprint only, Blank template, Desktop / Console - Maximum Quality - No Starter Content)

3- Create a new Blueprint Class based on Actor, name it “BP_Parent”

4- Create a second Blueprint Class based on Actor, name it “BP_Child”

5- Open “BP_Child” Blueprint

6- Add a boolean variable named “isChecked?”

7- In the Event Graph: Plug into the ‘execution Pin’ of BeginPlay a ‘Print String’ to display ‘isChecked?’ value on screen

8- Compile and save “BP_Child” blueprint

9- Open “BP_Parent” Blueprint

10- Add A Child Actor component to it by doing a Drag and Drop of “BP_Child” into “BP_Parent” component attached to the DefaultSceneRoot

11- Select Child Actor component and in the Details panel expand the ‘Child Actor Template’ category, expand the ‘Default’ category and
check to true the boolean ‘IsChecked?’

12- Compile and save “BP_Parent”

13 -Place “BP_Parent” in your world level

14- Hit play

The print string display “True” that is ok at this time! End play

Steps to reproduce bug:

15- Open “BP_Child”

16- Compile and save it

17- Hit play

and it display “false” and it should display True !

Note: if you compile BP_Parent before play you will get “True” on screen, if you compile BP_Child before play you will get “False” on screen

it mean our game wont run the same depending on the compilation order :x

Hello again ,

I was able to reproduce your issue with the repro steps you provided. I have logged a report for this issue which you can view here:

You can track the report’s status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.


i found a new behavior to get the good expected value, that may help to debug this: if you move the “BP_Parent” a bit in the scene before hit play (translate it along x axe for example) then it will display the good value

so we have two way to get good value:

-Compiling BP_Parent before hit play
-Move a bit BP_Parent in the scene before hit play

Note that in my step by step project i gave u, it is a bug about variable, but there others bug with component added that i didnt explain here.

It is important to note that: in my game project where i have this bug, it seem that the solution of moving a bit my blueprint in the scene, before hit play, fix it better than compiling it

i dont know why but components and variables work fine when i move a bit my blueprint in scene before hit play.

if i use the compilation solution before hit play only variables seem to be fixed but components have somes bugs

i hope you put this in a high priority bug to fix because we cant use child actors at this time

There is a bug with -child actor component-
BP_Collision is a simple blueprint that add a box or sphere collision component following a variable. I intend to use it as child actor component.

Look i have a BP_Actor in my scene that have a -child actor component- based on BP_Collision blueprint.

At this time everything look ok, the BP_Actor has a child actor component base on BP_Collision and the child actor template has the variable collision shape set to Sphere

Ok this work fine.

But now if compile the BP_Collision blueprint, here is what happen :

Wtf ? My BP_Actor blueprint now has his -child actor component- making me a BOX COLLISION instead a SPHERE !
So i go check my BP_Actor to see if my variable is still set to a sphere , and it still set to a sphere (see below). Wtf he make me a box when i compile the BP_Collision?

If i try to play my game, it still make me a box instead a sphere !!!

To get the correct shape back, i have to recompile BP_Actor again

If i compile BP_Collision, Boom my BP_Actor will have a again a BOX SHAPE instead THE SPHERE !

If i compile BP_Actor, Boom it fix it and my shape is now a sphere

You can download the zip project to play with it MEGA