The little Frenchman returned to Chelsea's training facility on Tuesday to begin training for a possible relapse of the season, but after that, the 29-year-old has chosen to stay at home, a decision supported by the club.
Kante had an incident in 2018 when he fainted during a training session and his brother died of a heart attack the same year.
Chelsea do not know when Kante intends to return, the BBC writes, but the club takes his concerns very seriously and has not tried to persuade him to rethink.
Joint training for Premier League clubs began this week with the hope that series pellets will resume in mid-June.