Well, first of all there's a performance preferred tempo vs default tempo issue. E.g. performance preferrable tempo is 130 bpm, while default tempo is 120 bpm. Tempo of midi file with a click track is 120 bpm as well, but it supposed to be played in the performance preferrable tempo. But sometimes it's played in 120 bpm instead of what's written in performance settings.
Another glitch is click routing. You all remember song "The Final Countdown" by Europe. The band I'm leading played the song last summer on a couple of parties. Since the band lost a solo guitarist again (not the first time, and I'm afraid not the last either), the famous guitar solo originally played by John Norum was being played on keyboard. I've decided to make two performances, one for the whole song save guitar solo, and another for solo, with a pad for a left hand and guitar-like lead for a right hand. There's more than enough time to switch from the former perfromance to the latter, and barely enough to switch back in the end of solo, but that's OK. Suddenly I've found out that when I switch from the former performance to the latter (before guitar solo), the click sound goes not only to the SONG/CLICK OUTPUT, but also to a main output, so the audience is hearing it!
Since I've did not use arpeggiator in the song, I've just stopped to use the click track in it, but the problem might surface again, so I'd like to know why it happens and how to prevent it.