When applying a transform in a Blueprint using Set Actor Transform, location and scale work fine, but the rotation does not get applied at all.
The actor itself is a pawn, and only has a camera component attached to it. It seems that no matter what I do the rotation keeps getting forced to (0, 0, 0).
I was able to recreate your issue by creating a new blueprint with parent class Pawn. Then I included a Camera asset as the Root component. In the level blueprint, on BeginPlay I set the SetViewTargetWithBlend to that camera, and in the blueprint of the camera itself I used SetActorTransform to spin it. The game started, my view was set to the camera position, but the camera didn’t spin.
This is what I did to fix it. Go to the Components section of your blueprint. Select the camera component. In the details box remove the checkbox that says “Use Controller View Rotation”.