Had a similar situation with a hidden city ticket, AAA-BBB-CCC, planning to exit the airport at BBB and not continue onto the second flight.

First time that I did this, there was no RR points awarded. Called CS and was told to cancel the second leg before its' departure and the proper credit would be given. When I had the opportunity to do this again, and cancelled the second leg (in your case MDW-OAK), the points showed up.

If this is still true, there is nothing you can do now. Had you canceled the rest of your reservation while in MDW, credit would have been awarded.