When loading a save, if the save is in another scene than the current scene, the main camera will be used instead of the camera set by default in the settings.
Unless you've added a Constand ID component to the active GameCamera, this is not a bug.
You should be getting a warning in the Console when you save the game while the active camera has no Constant ID component.
In order for a scene object to be "visible" to the save system, it requires a Constant ID number, which can be assigned either by adding a Constant ID component, or a Remember component.
Remember components are only required if any changes about the object itself need to be recorded - otherwise a Constant ID component is only necessary. This is covered in Section 9.2 of the Manual.
Comments
You should be getting a warning in the Console when you save the game while the active camera has no Constant ID component.
In order for a scene object to be "visible" to the save system, it requires a Constant ID number, which can be assigned either by adding a Constant ID component, or a Remember component.
Remember components are only required if any changes about the object itself need to be recorded - otherwise a Constant ID component is only necessary. This is covered in Section 9.2 of the Manual.