I try reproduce the conditions of this problem. Here is a simplified design.
I create a datumPlane, selecting to attach on XZ plane.
I get this : the plane is visible on the XY plane instead of XZ.
I said "oops there must be a bug, I can't attach on XZ plane". Oddly, it's marked attached XZ in the left panel.
So I attempt to place my vertical plane using a trick. I select an edge on the rectangular pad of my design.
I choose to attach the datum plane on the inertial 2-3 axes of this edge and I get the right position (XZ) of this plane.
I thought that it was ok, and that I could then rotate this vertical plane to get it in the wished 45° position. But I can't change the positions of the plane because they have been fixed by FC with a 120° angle and an odd axis, to I can't modify this rotation if I don't want to compute an inversion and a product on 3x3 matrices on a spreadsheet, which could take me hours !
So, perhaps the problem comes from a misunderstanding of FC and PD interfaces. It seemed to me so straightforward to choose to create a datumPlane on the XZ object plane and then rotate it according to my needs. I suppose that a trained user could tell me that neither of the two attempts explained here should be used and that the right way of doing things is... Well, perhaps there is a bug somewhere. I don't know.