In Content Settings, General Tab (first screenshot), try changing it from 'Include' to 'Exclude'. You've told JoomlaComment to only include some item/category/section ID's. While you have chosen Section and Category ID's, the Item ID is blank. That means "Only include these Items : [None] from these Sections/Categories : [Whatever]".
You'd be better off setting to 'Exclude', which is effectively the same as saying "Include all, except for these: [Whatever]" - then you can leave the Item ID's blank. Then, hold CTRL and Left-click on the Categories and Section in the list that you do
not want JoomlaComment to appear on. Do I make sense?
I think that's the reason why you can't see it. I know, the backend design is a little complicated