I too saw this issue over the weekend. For me it wasn't that it wouldn't work, but wouldn't update as I drove. If I exited navigation and reentered it would find my updated location and stay there. I am on RR and love it else wise.
That is what...
I realised the GPS location doesn't work since I installed CM12.1. I deleted everything to make sure it was nothing I installed or modified afterwards. I tried RR from scratch too, and the problem persists.
Any help will be greatly appreciated