Why you type a certain amount of words, they disappear when you click enter. It has been going on since 0.7.4. It hasn't been fixed. Here are some screenshots of what I am trying to explain. I'm in 0.7.6 right now. Still nothing.
For both Creative and Survival, including Realms servers, and Local Servers, not to mention External Servers.
Duplicate of MCPE-5250