Actors can be copy-pasted from hidden layers, which carries with it bHiddenEdLayer state.
"It looks like this could be prevented in UUnrealEdEngine::edactPasteSelected, by setting bHiddenEdLayer to false when ensuring the pasted actor's layers are all visible. bHiddenEdLevel is also transient while bHiddenEdLayer is not, that might be another thing to explore.
Also worth note is that if you paste the copied actor into a text file, you will also observe that the object has bIsEditorPreviewActor set to true. Should this have been cleared, maybe in FLevelEditorViewportClient::DropObjectsAtCoordinates() when bCreateDropPreview is false?"
Result: Hidden actor is pasted into the level with a visible layer and, after clicking 'See Contents' on the layer in the Layers window, you can toggle the visibility of the pasted actor with no effect.
Workaround: Toggling the visibility for the whole layer will correct the issue.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-65160 in the post.