Hmm, are you syncing via midi or trig?
Not too sure about the SQ-1's trigger but did have the impression that it was variable, whereas the Volcas are 2ppq (thus not syncable to a BSP via any of it's analogue sync modes).
Check your SQ-1's manual to see what the sync modes are how to change it, then set your BSP via MCC to one that matches that which you have set the SQ-1 to.
With midi, one thing to remember is the BSP doesn't send a constant midi-clock signal, so if you aren't running the BSP, nothing that needs a midi-clock signal to run will run (such as other midi sequencers in slave mode).
