Some observations.....
The sketchup offset tool is not consistent. It does not always provide the same result....sometime gives the left, sometime gives the right.
They are slightly different.
Both results have two faces, a bigger face and a small one(the hole).
The bigger face is selected in both results, while the small one is not selected.
On the left, the small one is separated from the bigger face, i.e. the bigger face contains a hole.
On the right, the small one is overlapped with the bigger face, i.e. the bigger face does not contain a hole.
.......
offset_diff.PNG