I hardly use BB mainly RB, so if you would like to try this Slave Sync Live Professor Free to Realband/Biab/PT in BB and see how it works for you until the VST Sync problem is fixed.

SR

Would be great to do it the other way around, to use (e.g) CUBASE as the master and BiaB as the slave.
I very often "steel" some BiaB guitar licks to incorporate them into my Cubase projects. This would really speed up the process of finding matching real tracks.

SC

You can try Realband > Options > Sync Source
hit play and it should wait for Cubase.

In Cubase Transport menu > Project Synchronization Setup > MIDI Clock Out > select MIDI Clock eg: LoopBe

You can also load chords from BB to Cubase http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=289338