Sorry that my fix didn't work for everyone. It's still a bit dodgy on my gf's phone. She sometimes can't get it to work and can't end calls. When I try, it works fine. Maybe put it up to your face to see if you can get the proximity sensor to turn the screen off then on again enough to type something in.
I read about a different phone experiencing these issues that was the result of a faulty proximity sensor. Might be the case on some of the Lucid's, or maybe its just a software glitch.