Billboard changes from Portrait to Landscape


I have some floating clouds in a scene and I’m using billboard to make sure they’re always oriented towards the camera and the user never sees the paper thin edge when they move their camera around.

It works great but only in landscape mode. When I go to portrait mode it looks like all the clouds are rotated 90 degrees in the y axis.

How can I can I get it to always be the same (as in landscape)?