Since I installed Ubuntu 18.04, Tilix suddenly stops working with Nautilus:

No "Open Tilix Here" entry in right-click menu.

Shortcut key to open Tilix from Nautilus window doesn't work.

At first, I thought that Nautilus changed its API and broke its extensions. Fortunately, from this GitHub issue, it is probably that it is packaging issue, though the case mentioned in the link is for Fedora (while Ubuntu is Debian-based).

So I tried to install gir1.2-nautilus-3.0. Bravo! Tilix's Nautilus extension works again.

So coincident that the guy who packages Tilix for RPM system and the guy who does the same job for DPKG system are consensus about how Tilix's dependency should be. But it is not good for us as users when we don't know why our favorite terminal emulator stops working as we want.