Hello dear Dorico team,
I hope you are all doing well there! 
I would like to report a bug that occurs on cross page glissando.
There is no gliss continuation attached to note on the next page.
I hope it could be fixed in the next Dorico release!
Best regards,
Thurisaz
I have this same issue in one of my scores where the harp figures prominently.
It appears to only affect glissandi that begin on one staff and end on a different staff.
if the gliss starts in the lower and ends in the lower at the page turn, then the glissando continuation line appears.
If the gliss starts in the lower staff but ends in the upper staff at the page turn, the continuation line disappears.
I THINK the devs are aware of the issue.
Please see this thread.