I rolled back just the "Sound Blaster Audio Controller" which was updated a few days before (in Windows Update). This update caused the issue with the headphone connected to the front connector. The roll back corrected the problem.
Sound Blaster Audio Controller (in Device Manager)
I solved the issue reverting driver 6.0.105.8 June 19, 2017 to 6.0.103.34 February 7, 2017
Windows 10 Pro 1703