Create a “Make Transform” Node in a Blueprint Actor Construction Script.
Type in a value for X Y and Z for Rotation. I chose 999 X, 555 Y and 444 Z. (Random values).
Right click the “Rotation” struct and split it.
X becomes 555, Y becomes 444 and Z becomes 999.
This seems to happen for other nodes as well, that also have a Rotation struct (such as the “add instance” node)