Using Ubuntu 18.04, Audacity 2.4.1 from PPA.
It seems that Edit>Clip Boundaries>Next Clip does not go past the start of the last clip in a track. This is unfortunate, as it seems there is no way to go to the end of the last clip in a track directly with the keyboard, as when the tracks are different lengths, End will just go to the time of the end of the longest track.
Am I missing something?