That's how Hijack works. When an app (in this case, emphatic) is running in the foreground, the Hijack menu is unavailable. I asked for a mechanism for bringing up the Hijack menu from a user application, but did not have my wish granted.

If you want to go into the Hijack menu, you can select the "Hide" option in the emphatic main menu, which will temporarily put emphatic in the background, and put you in the Hijack menu. Once you're done with the Hijack menu, you can go back and select emphatic again to bring it to the foreground.