According to Variety, Fuller didn't leave Discovery voluntarily. He was allegedly pushed out.
It was originally reported that Fuller, who has extensive experience as a writer and producer for various Star Trek series including Deep Space Nine and Star Trek: Voyager, had passed the torch to executive producers Gretchen Berg and Aaron Harberts because of his other commitments. Fuller eventually stepped away from Discovery in full, citing work on American Gods as his reason.
But according to the report, sources within CBS say that Fuller's innovative and creative style — a style that isn't exactly focused on deadlines and budgets — wasn't a good fit for CBS and may have led to his departure.
A significant missed deadline that may have contributed to Fuller leaving Discovery involved scripts for the series that were months overdue. Executive producer Alex Kurtzman told the magazine that when he and Fuller informed network CEO Les Moonves that the show wouldn't make the publicized January premiere, Moonves wasn't thrilled, but took the news well.
"It wasn't his favorite news, but he totally understood," Kurtzman said.
A month after the conversation, Fuller was no longer connected to the project.
Despite no longer being attached to Discovery, Fuller's influence remains. He is still listed as the show's co-creator and shares story credit with Kurtzman. Fuller also has a screenplay credit for the show as well.
Star Trek: Discovery will debut on Sept. 24.
Set 10 years prior to the five-year mission of the Enterprise in Star Trek: The Original Series, Star Trek: Discovery follows the adventures of Starfleet on their missions to discover new worlds and new lifeforms, and one Starfleet officer who must learn that to truly understand all things alien, you must first understand yourself. The series will feature a new ship, new characters, and new missions while embracing the same ideology and hope for the future that inspired a generation of dreamers and doers.