Hope this is the right place for this.
Seem to be encountering a bug with lyrics and staff hiding in Dorico 3.1
Steps to recreate:
Create two or more vocal lines within a chart and a piano staff underneath
Say line one is a lead vocal line and then staff two is BVs which are more sporadic with their entries
Entering lyrics for staff two works as expected however jumping across large sections using the space bar (i.e from the last BV lyrics of a chorus to the first of a subsequent chorus) seems to override automatic staff hiding, leaving you with multiple systems containing empty bars.
Delete the last lyric of the first section, re enter the lyric without pressing space bar (just click away from the popover)
If the lyric is over a melisma and you require a line extending from the lyric then you can add a random note at the end, enter the lyrics (using the space bar to generate the line) and then delete the extra “stopper” note.