McCormack denied there was any fallout when asked about it by Us Weekly in September, calling the reports "crazy".
"I think people worried about that entirely too much," he said. "The four of us get along like a house on fire, we always have."
He insisted the show was ending simply because the producers wanted it to go out on top.
"Will & Grace" originally ran for eight seasons from 1998 to 2005.
In September 2016, the cast reunited for a 10-minute PSA urging Americans to vote in the 2016 presidential election; following its popularity the show was renewed for a ninth, and then tenth and eleventh season.
TooFab has reached out to Mullally and NBC for comment.