I found my error in my case. Maybe this helps you tomslowcat:
I was using Toontrack Superior Drummer and EZBass in my case and I had built the Midi inside that program rather than in S1. So S1 had no Midi track information at all, so it had nothing to transform... To fix, I dragged all the Midi out of Superior and placed it on to the S1 arrange track and muted all the regions in Superior, then it would transform.