In some cases, VocAlign may fail to update its' UI when your Output audio finishes processing.
In these cases, the Output status will continue to show a spinning icon instead of the expected "Ready" text:
Please try clicking the spinning icon, which forces a refresh.
Assuming the Output is actually ready, this will quickly display a "processing" window, then switch the Output status to "Ready," display your yellow Output waveform correctly, and allow playback of the aligned audio.