I have 3 profiles that I'm trying to loft together around a 90 degree; a start, middle and end. Start and middle are the same profile. I then have 2 guides, an outside and an inside, the outside is a curve I'm trying to follow and the inside is a right angle. My problem is, no matter what I try, I can't get the inside to stay square. I'm almost thinking I have to create additional profiles every X degree between the 0-90 instead of just my 0,45,90 that I've constructed.

As you can see in the screen shot, the inside has a slight upsweep on both lines of the "sketch5" profile.

Sketch 1, 2, 3 control the overall shape

Sketch 4 and 5 are my guides

If I add both guides and change to Section view, the very center of my loft shows squared, but my outer edges have the curve. Also the outer ends start to tweak on the curved side of the profile when I add the inner guide.

Adding additional guides on the ends helps square off the inside all the way across, but then jacks up the outside at those ends even more so?

Any help you guys have would be awesome.