I am having the exactly problem.
The problem is that you can't use Arabic and other Asian language together. When you are using Arabic input with Japanese or Chinese input as a language pair, Arabic input will not work correctly.
Say, you are making a biligual document in Arabic and Japanse, you switch to Arabic input after typing Japanse, Arabic input will just work as an English input, no Arabic character is shown at all. There's is a work around though, when you finish working with Asian language, make Arabic and English as language pair, then you will able to input Arabic. It is annoying that you can't use Arabic together with other Asian language though.