It’s January 29, 2020 and almost same situation with my brakes happened last night. Driving on highway, stepped on brakes to slow down, they were “spongy” or took pumping to even slow down. Pulled off and had to coast to a stop as brakes finally failed. I called Dealership service Department immediately (it’s a new pickup, have 1,000 miles on it). They sent a tow truck and towed it to their service department. I’m waiting to hear what issues are and have it repaired. I couldn’t imagine continuing to drive it even if it were to go away after sitting for a bit (I didn’t turn back on to test brakes again). At the very least it needs to be checked out and me told what is causing this, then repaired. Then repaired or a resolution to issue found. I’ll report back what they found. It was pretty shocking to be driving along then realize my brakes weren’t working. Coasting to a full stop immediately and calling service was the best decision for me. The dealership was very helpful and promptly sent a tow truck. Hopefully they continue to resolve this.