Reference variable value disappears in child BP instances after changing the name of the variable in the parent

Hello,

For some time now I experience a problem with reference values in editable variables. Today I found out how to replicate this issue:

  1. Create BP_Parent.
  2. Create its child, name it BP_Parent_Child.
  3. Create editable Actor reference value in BP_Parent.
  4. Place a few BP_Parent instances and BP_Parent_Child instances on the level.
  5. Using picker choose some other actor in the default scene (some static mesh actor for example) and set this way all BP instances.
  6. Change the name of the reference variable in BP_Parent.
  7. Relaunch the editor (important!).
  8. After reopening the editor values of the variable will be set to None in all instances of BP_Parent_Child.

It looks like saving the level is not required for this issue to appear. Relaunching the editor is important, because sometimes this issue occurs just after renaming the variable and sometimes not, but always after reopening the editor. That made it hard to follow at first, because it is possible to work without problems after renaming without exiting the editor.

It seems the problem is more complicated than what I described above. My project is getting bigger and I start to notice more and more disappearing reference values even without touching BPs at all. I would say it is a major issue that makes reference variables unusable. Will attach more info if I learn anything new.

I found a temporal workaround. It seems values disappear only if reference variables are inherited. So I created new variables for child BPs and set them as values of inherited variables on BeginPlay. Ugly fix, but it works and I don’t need to set everything again and again returning to the project.

Hey Nox_A15,

Thanks for the report. This is a known issue that was logged as JIRA UE-34488. It’s been fixed internally and I just verified that it does fix the exact issue reproducible with your steps. The target fix is currently for 4.16.

Cheers,

TJ

Thank you for the info TJ! Great to hear that. :slight_smile: