I had issues with offset tool where it creates a new sketch and other times offset lines is on the same sketch.
I now figured out if you select the face of the sketch the offset creates new sketch.
If you select just the lines offset stays in the same sketch.
Looks like a feature but shouldn’t offset just stay on the same sketch?
I’ve learned to use the sketch item in the left sidebar for selecting sketches for almost all operations.
Here is what happens, 2 different behavior for offset.
Offset starting from Sketch Face, need to project the offset back to the original sketch.
Offset starting from Sketch Edge, offset on the same original sketch.
I have also found this doesn’t happen all the time.