I had to rename my husband "My Love" and that works flawlessly. Incoming calls/texts show up as ICE (since his number is in my ICE contact) but it made voice command work. Doing the same with my daughter didn't solve the problem. Her name could be spelled many different ways and I got tired of spelling it when using voice command so I created an entry with her nickname. The nickname shows up when she texts me but when I voice command it, the contact list comes up and I have to scroll through to it.
I have no idea why it works with my husband and not my daughter.