David Did you try going to LinkedIn with a different browser such as Firefox or internet explorer? Not really my area of expertise but googling this issue it appears others have the same issue.
I think the best way to answer is to ask a question: Are all of your writing gigs exactly the same? If you're like any of my writers you know that every project is different. They're different in length
There is no surefire method of telling whether or not a site is legitimate or not. But there are some ways that you can judge a site. Does it have security? -- If it does it'll have an S after the http