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images disappear from the bottom box(image box) when i hit publish in the portfolio area

at the end of the video when he uploads the images one after another and then adds a fetured image and hits save/publish his stay in the tab. when i do it they disappear and when i try to preview the page the lower area where my images were (but there no longer) is highlighted red showing theres an error. whats wrong and how do i fix?