You can add line from the “Lines” menu. It’s visible on slashes but needs vertical adjustments with text in the engrave mode.
I think there’s just a little bug here. If you click Show Other Voices, as @Derrek mentioned back in May, then it works fine. The odd thing is that once you have it showing, you can then uncheck Show Other Voices to hide the music underneath and the PT will still show. Seems like an odd design if that’s intentional.
Anyway, it appears like it still works, you just have to trigger Show Other Voices on then off.