SOLVED
Thanks Phil - it's working-- Bad MIDI cable made me think it wasn't. Sync is working fine and I like it that, if the sequence is not playing, the tap tempo will still work.
I cannot get the midi clock from my sequencer to affect the tempos in Helix. What am I doing wrong? Where can find good documentation? I'm using an MPC 1000 sequencer - it's midi out is plugged into the midi in of the Helix. Nothing is happening at all.