Other players cannot see my chat messages

When I type in the chat box and enter it, more often than not, noone responds. I've attempted to get peoples attention bye typing "who wants free diamonds?" in case they just didnt care, but no matter what I say noone responds. This only happens on servers; The Hive, Lifeboat, Mineplex, Cubecraft, Galaxite, and the dreaded Mineville. It ruins the game experience for anyone effected who wants to have player interactions or is new to the game. I am struggling because I am new to survival mod on Mineplex and I cant ask other players questions. Whatever is causing this bug only happens to some players because SOME lucky people can type in chat. Take note that commands such as /tp(a) and /getpos work, so I can type in chat and the game recognizes it but it mutes any other message. Thank you in advance for looking into the problem.

               Yours truly, Turg the Retarded.