Description

When a class is edited / hot reload preformed, code based components are sometimes removed from the MyBlueprint > Variables section and cannot be dragged from the Components tab into the graph with an error saying "Cannot find corresponding variable (make sure component has been assigned to one)"

I found this was most likely to occur when adding dynamic binding for component overlap / actor overlap events

Workaround:
Restarting the project after the hot reload will reset the components / variables and allow them to be added to the graph again.

Regression:
Yes - this behavior does not occur after hot reload in 4.17.2 (CL 3658906)

Steps to Reproduce

Repro Rate: 8/10

  1. Download attached project
  2. Create a blueprint based on MyActor
  3. With both editor and VS open do the following
    • Attempt to select / drag component from Components tab to Graph after each compile
  4. Uncomment lines 26&27 in .h & line 12 in .cpp (add MyMesh)
  5. Compile through VS
  6. Re-comment line 12 in .cpp and uncomment lines 29&30 in .h & line 11 in .cpp (replace MyMesh with NewMesh)
  7. Compile through VS
  8. Uncomment line 12 (both MyMseh and NewMesh added)
  9. Compile through VS
  10. Uncomment lines 32&33 in .h & lines 13, 15-17 in .cpp (add TestScene and setup hierarchy)
  11. Compile through VS
  12. Uncomment lines 35&36 in .h & lin 14 in .cpp (add Skellington)
  13. Compile through VS

Result:
When a component is selected in the Components tab, its Details are not displayed. When this occurs, the component cannot be added to the Graph. The Component's Category also disappears from the My Blueprint > Variables section

Expected:
Preforming a hot reload allows previously existing and newly added code to function together.

Have Comments or More Details?

There's no existing public thread on this issue, so head over toAnswerHub just mention UE-50559 in the post.

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Fixed
ComponentCore - Hot Reload
Affects Versions4.18
Target Fix4.18
Fix Commit3682918
Release Commit3682918
CreatedSep 29, 2017
ResolvedOct 9, 2017
UpdatedApr 27, 2018