If you mean
Nicholas Sparks, then this novella is by a well-known NYT bestselling writer, not a first timer.
Is this a reprint of his first effort? I don't read him, so I don't keep up with his stuff. If it's his first, then he was danged lucky they took him on.
Short works sell, but usually not from first novelists unless they've got one hell of an agent and cover blurbs from bestselling writers in the field. Or they better be one hell of a writer!
Janet Evanovich has a series of "between the numbers" short mysteries that run at about 45-50K words. They're just too short (to me) to justify charging a hardcover price, but they sell all the same.
They retail at a 6.99 paperback price, which is only a buck less than some full length works. They look "big" because the publisher messes with the font size and line spacing so it has the same page count as a larger book.
I'd rather have a thinner book for 5.00 than a fake fatty.
They sell because she's a good writer. I love her stuff myself, but generally borrow from the library.
And reference books don't allow for publishing house preferences.
Some will look at works of any length, but others, especially for genre fiction like romance and S.F. & mystery, have a minimum/maximum length that varies.
Category romance lines are especially strict. If they want 58K words and no more, then don't give them 60K or it will get trimmed.