Snapping in 2d and 3d is different

Hello everyone. I am trying to add some extra faces to my 3d design but when snapping to the edge of the circular part it snaps to another line near the real circular line. Here is an example: 

When I try to add a line inside of the inner hole:

Here the green part is the real bounds. But in Sketch mode the snapped bounds are different as seen above.

I have tried this many times in many 3d models but resuklt is the same. It doesn't snap to the real bounds of the circular shapes. Do anyone have an idea?