The Swiss Football Association announced, according to the newspaper Blick, that Embolo's electronic travel authorization (ESTA) was initially approved, but it was later reported that it still needs to be reviewed.
The 29-year-old striker, who currently plays for Rennes in France, has scored 24 goals in 86 international matches.
The Swiss federation expects Embolo to get the green light by Wednesday at the latest.
According to AFP, Embolo received a suspended sentence in April over threats made during a night out in Basel in 2018.
Switzerland will face Qatar in its first World Cup match on June 13 in San Francisco. The other teams in the group are Canada and Bosnia and Herzegovina.
