Please see the attached screenshots and project file. For some reason I cannot randomize the rotation of my particles along only the X/Y axis, even though Z is set as the Orientation Axis. Is this a glitch?
Note that this is using the default cube, no changes have been made to it.
Project File: https://www.dropbox.com/s/yfq38ryg3ih2jwx/z_up.blend?dl=0