Channel panel missing

Hi, somehow the channel pannel got missing on the left side of any track,
where I could adjust the fader in the past.

As you can see in the picture.
How can I solve this problem ?
Waiting for your reply.
Thank you.

EDIT, maybe solved : Now I can see the channel panel, because I could see it on the list when right clicking that area(where the arrow is) .
But before that, when I created the post, there was not channel panel, even when right clicking that area.
So what may have been the problem ? What if it happens again, what should I do? Is there a chance it can happen again ?