FWIW, I tried stepping through play-in-editor in Visual Studio (pulling source for release 4.15.0 from GitHub) and there’s no obvious exception getting thrown. The ReceiveBeginPlay() function gets called on each actor. However, when the PlayerCameraManager blueprint is created, the blueprint events stop firing. Bizarre.
I would suspect that perhaps something in the blueprint-ization of PlayerCameraManager is wrong, and ends up invalidating / corrupting the blueprint event dispatch? That’s kind-of vague, I know, but that’s about as far as I can get without diving way deeper into the implementation internals than I’m able to at this time.