This marks the second straight day the 24-year-old has been on the list.
Nylander, whose exposure to a possible positive COVID-19 case from a close contact outside the team led to him missing Wednesday's game against the Montreal Canadiens, will remain in the league's protocols until it is determined whether his exposure resulted in a positive case.
The Maple Leafs said Nylander will be isolating while further tests are conducted. NHL protocols, as noted by Sportsnet's Elliotte Friedman, require a player to self-isolate for at least seven days after exposure to a case of COVID-19, pending test results.
Nylander was on the ice for the Maple Leafs' morning skate Wednesday but, as Sportsnet's Chris Johnston reported, the early indication was the incubation period from when his possible exposure to when he skated with his teammates isn't believed to have been long enough for him to be considered contagious.
Toronto's game against Montreal on Wednesday was played without delay.
Nylander has 13 goals and 30 points in 39 games this season.