Opening "[" bracket does not work

Hello team, 

I have a weird problem on Zeppelin notebook, I have just started to use it and I realized that the key "[" doesn't work while it works in every of my other apps, so it is not a problem with my keyboard. Even stranger, the key "]" works, which mean that it is not an issue about special characters.

Would you have any idea where this problem can come from please ?

Thanks