Can't inherit from ALight without a linker error

This is a regression from 5.3. It should be possible to inherit from ALight outside of the engine module without any sort of errors.

Case: [Link Removed]

1. Create a class that derives from ALight in a custom project (see below for an example).
2. Build the project.
3. Observe linker error about a missing definition for ALight::PostLoad.
4. Expected behavior: no linker errors when deriving from ALight.

UCLASS()
class ATestLight : public ALight

{     GENERATED_BODY() }

;