I want to point out that you can achieve a similar result to this via an extremely hack method regarding bones in a skeletal mesh. Of course, it’s not as simple as using 2 parent bones, one for rotation and other for single-axis scale; Unreal doesn’t support that at all and any/all changes to a single bone’s scale will apply that to successive bone scales, which… is not what’s supposed to happen, as those bones are also supposed to have their world positions modified as well.
Either way, I managed to achieve a “flat character” effect by changing “Root” bone Y-axis rotation via blueprint, while having model itself face camera and flattening its local X axis. This is basically forcing what UE4 does not natively support, hierarchical transforms.
There were still issues and limitations, majorly in part because of root bone always trying to rotate on its local Pitch/Roll/Yaw meaning I couldn’t feasibly achieve a “3D sprite” effect, or more specifically, Rotate → Flatten → Unrotate in any arbitrary axis. This could possibly be fixed by forcing some transform matrices instead of simply dealing with rotators, and this is probably preferred method to begin with, but point is it’s possible, just very limited… and requires a lot of specific setup.
Doubt this is going to be fixed since Unreals priorities are seemingly fixed towards VR and like, not anywhere near fixing its fundamental low-level problems 