G'day Jon!
I'd normally select all 3 sides & change them to Gable type in one hit, so I can't see it being an "order" issue.
Only time I've had a curved roof go awry iirc was if I missed a 0 or added an additional 0 in the radius parameter.
The lower roof is the one that took a cup of tea and a kit kat to work out.
Could it be the order that I am changing the 3 roof types to gable?