Feed List Working fine, But No Posts

I have something like this. Posts are being imported but there are some links that come with feed/items/…. which always direct to “page was not found”. I am also using the social media auto publish plugin which shares all these posts to my media and the problem mentioned here makes my readers to get disappointed, cause they click to read but they find “page not found” message every time. I do not know what is the problem caused by, by this plugin or by thauto publisher, the only trick I noticed is links that come with feed/items/…. which always direct to “page was not found”