Help with Image Mismatch

I have an Image mismatch manual action: "Images from this site are displayed differently on Google search results pages than they are when displayed on this site". I think this is because I have done some images like img src="imgurwebsite/adas" so I have removed this. Is there anything else that could cause this? I have submitted a review, how long will this take? Will they tell me if they review it but don't lift the manual action?