Why siding inside?

[Gene Davis]

What causes this? An inside corner of exterior wall has siding showing inside, rather than having the drywall finish from the wall it joins wrapping onto.

The plan of the corner is shown, as is the plan of the auto generated attic walls above. There is a gable wall above this corner, spanning it.

How is this fixed without a complete rebuild?

[MikePreble1]

Take a close look at picture #2.
The exterior wall (heading from the door, going left) ends past the point of the corner (like a short-legged "T".)
It also looks like you have a pony wall, or half wall thing happening, which may also be part of what's happening.
Mike

[Gene Davis]

Thank you. I was able to move the end of the wall, which fixed the problem.