Cant find the Invert button

[defaulto58xqgkf8hiz]

I am trying to invert a mask but the invert button does not appear where it does for others. In a tutorial, I watched the invert button was in the bottom left panel next to mask. Can anybody help? Thanks

[Ali Jaber]

Usually, this means that your mask isn't closed, try to move the point on the bottom to check out (there should be two separated points).

[Mylenium]

The answer is in your image. Your mask is indeed not closed.

Mylenium