If we leave and later return to the quest "Hazy Cosmic Jive" with the goal "go to Zigi's estate" it seems to be impossible to progress. There are "shadow wall" force-field things blocking both doors between the courtyards (by the Shadow Sentinels and Trickster Jack) which is where the quest arrow sends us, and no other visible way in. The sewers might still be passable, but the quest arrow doesn't take us there and they are otherwise hard to find, and may not be open?
Unfortunately the quest helper is unable to point you in exactly the right direction here due to technical limitations. You'll need to travel through the sewers to arrive at your destination. We are thinking of recording a new line of "helper" dialogue that would play here for when others might run into this situation in the future.
