I can not use chat on official servers.

This happens to me a long time. I can not use chat on official servers, I can send messages, but no one can see them, I do not receive any error code or anything. It's not a punishment of the servers, I've already contacted Mineplex and Lifeboat, but they say I'm not punished.

It is also related to plaques, when I put a plaque on the floor, but it does not save anything I write. I have to write a lot, from a number of characters it saves my message, this has been happening for a long time and I have seen several other people with the same problem. This is very strange, but it really messes up my game, is it a punishment in my Xbox account? I do not know, I just want help ;-;

Video for a better explanation (Sorry for the music in the background): https://www.youtube.com/watch?v=GsMUfGFOtsk&feature=youtu.be