DeferRunningConstructionScripts has been added as a workaround for a issue by asynchronous mesh compilation, but it doesn't consider BeginPlay.
Therefore, if DeferRunningConstructionScripts is executed when OpenLevel in the editor, BeginPlay will be executed before ConstructionScripts.
We need something like DeferRunningBeginPlay to solve this. Perhaps the simple solution is to add a process for BeginPlay to the FActorDeferredScriptManager.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-157303 in the post.