The Great Gatsby! question :)?

I'm reading Scott Fitzgerald's clic, I'm in grade 12. It's not a required reading material in my country, but I'm reading it for fun :) I'm actually enjoying it, and as usual when I read clics I read every single little thing in there to find out all I can about the book before I actually read the book (a tip I found was genius after I read Crime and Punishment and was confused after--I read the notes and it helped me understand a lot more). In the notes of The Great Gatsby it mentioned that it was not a popular book in Fitzgerald's time. Why? Charles Scribner III apparently adored it. Haha, that's my question. Why did people not like The Great Gatsby when Fitzgerald was alive?