'MIDI input in step time won't' - please, what does that mean?
Is Sib7 getting some data, invalid data, or no data? If it gets data ok in real time, and in step time it's getting nothing, then something is not set correctlt in Sib7 and I'd think it's waiting for timing data which it's not getting. Could also be something in the keyboard which is still sending timing data which is confusing Sib. You need to check settings and make sure Keyboard is NOT sending timing data, and Sib7 is not expecting any.