Struggled with TouchPal 4.8.4 since yesterday. It turned out that the new version 4.8.4 from Android Market is bad for Galaxy 7 Plus. Uninstalled it and copied from my Kindle Fire then installed it 4.8.3 on Galaxy 7 Plus. It's working now.
The problem was the keyboard displayed were using big font and the keyboard partially blocked. Thus can not type any keys to the right of N.