I merged your new thread into this one as it is the same question.
OK, so I have two songs with the same title and artist on both the client and the host. Both client and host have different PDFs attached to that song. On the host "Send PDF Documents" is disabled, on the client "Show Local Lyrics" is enabled. This works just fine (tested again right now).
So if it does not work for you, you most likely have not the same title and artist set for that song on both iPads. Please check that there is no typo and that both tags are set.