I can see the dimensioned sketch (light blue lines) on my part, but cannot select the sketch to Extrude Cut the channel I created.

Also, when I did have access to the sketch, when I tried to select the circular path from small hole to small hole, it said the path was open or undefined (I'm paraphrasing), I believe the whole plate was being selected.

Do you see anything wrong with the path?  The lines were chosen to be tangent to the holes.

Lastly, the upper edge of the path on the lower hole is not tangent, and I was having trouble editing the line to be tangent.  ANy suggestions as to how to make the line tangent (once I regain access to the sketch)?