I've recently put the forge version of Dynmap on my server, and although it works great otherwise, it seems that i can't get the webchat to appear in-game. Does anyone else have Dynmap on their FTB server, and if so, have you had this problem?
I know this is an old thread but to answer the question, it's because dynmap uses the chat protocol through the back side of the server. Much like you could chat to players in bukkit through the admin panel (not to be confused with the console). Since FTB servers never technically "start" according to these server managers you cannot chat.
Hope this made sense, sorry for beating a dead horse.