Looking into this myself, it seems the CameraAnim type is missing the ‘BlueprintType’ definition in code.
Should be a simple matter of changing:
// Engine\Source\Runtime\Engine\Classes\Camera\CameraAnim.h
UCLASS(notplaceable, MinimalAPI)
class ENGINE_API UCameraAnim : public UObject
{
....
To:
UCLASS(notplaceable, BlueprintType, MinimalAPI)
class ENGINE_API UCameraAnim : public UObject
{
...
However there may be a specific reason this is the case, so I am dubious about making this change myself.
TL;DR: It’s been left out on purpose. (probably.)