Do keywords actually sync between LR Classic & LR CC?

I have been trying to sort out a workflow where I can use the Sensei facial recognition to group people in LR CC and add keywords to their photos so the actual files can be sorted in LR Classic.

I am finding though that if I add a keyword to a photo in either program it doesn't show up in the other program (btw sync is on).

Any thoughts on what is going on here?