When a component that is included in a blueprint by default is set and placed in the viewport, the instance of the blueprint is not updated in the viewport if the yellow arrow is used to reset the component to its default. This does not apply to any component that is added to the BP after it is created.
1. Open UE4Editor (any project)
2. Create new blueprint with StaticMeshActor set as parent (MeshActorBP)
3. Select StaticMeshComponent and set the Static mesh
4. Add instance of MeshActorBP to the viewport
5. Inside the blueprint, select StaticMeshComponent and click the yellow arrow next to Static Mesh in the details panel.
Static mesh in BP is set back to none but the instance of the BP in the viewport does not update.
Opening the static mesh drop-down and selecting clear instead will update in viewport
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