This apparently happens a lot. The authors of books and writers are at the very bottom of the totem pole. Which is another example of how backwards hollywood is...the very people who CREATE the thing are least valued.
I recall Winston Groom had to sue over Forrest Gump because the studio tried to claim they didn’t make a profit. If memory serves, his cut came after all “expenses”. I don’t recall the outcome of the suit, but to claim that movie didn’t make money is simply laughable.
I read several years ago that William Shatner never received any royalty payments for the original Star Trek series because according to the studios it still hadn't turned a profit. IIRC, it worked like this: Studio 1 had the contract with the cast members, and had to pay them once the show turned a profit. Instead of renting it out for television at a profit, they rented it to Studio 2, (which was a part of the large corporation that owned both studios) at far below market value. Studio 2 rented the show to television stations and turned a ton of money, but Studio 1 showed it as a loss each time they rented the show out. Shatner talked about Desi-Lu (still owned by Lucy, then) screwing them royally. They required Star Trek (which was made by a production company, Desi-Lu was the distribution company) to buy their props from the Desi-Lu studios, and charged them something like $500 for the communicators (this was in 1966, when pro football players made $10,000 a year.)
People involved in the entertainment industry are dishonest.