I have 4.6 and mojo and was recently frustrated by the same problem. It fixed itself, and I have no scientific path…BUT….
I went to the audio input/output settings via the audio meter, and flipped thigs back and forth, and rebooted. I also made sure the digitize settings were in DV input before the reboot, and made sure the DV deck was on and had a tape in it when rebooting…(cold, a new restart). Everything woke up at that point.
Hope this helps, BC