Scott did an hour long interview for FNAFs 10th anniversary earlier this month, and he was asked about collaborations. He said that he’s much more open to them now then 10 years ago, but that it’s really important and difficult that he maintains the series identity and integrity.
He also said the biggest challenge in getting a movie script right was balancing the animatronics roles as the threat, and as confused children who don’t actually have evil intentions. If I had to guess, HHN fell through this year because Scott had similar issues with the story. The second film will have way more animatronics, all of which are just straight up evil, so I think waiting for a sequel to do an HHN house might end up being the right move anyway.
He spoke very highly of Universal and Blumhouse and mentioned being excited to work together more, so I don’t think it was necessarily some big fight that led to FNAF not showing up at the event this year