The team did not specify the issue Clifford is dealing with and said there is no timetable for his return.
Clifford missed Monday's game against Orlando.
The Hornets beat the Magic 104-94 to snap a four-game losing streak. The team said at the time that he was absent due to an illness.
Special counsel details $6.7M spent in early months of Russian Federation probe
The spending was summarized in a report released Tuesday, the first of what Mueller's office said will be twice-a-year updates. That analysis also found that Mueller's investigation is accelerating more rapidly than previous inquiries.
The Hornets are 9-13 this season, Clifford's fifth with the franchise.
Clifford, 56, was hired as head coach of the then-Bobcats in 2013 and led Charlotte to a playoff appearance in his first year.
Silas typically shares the scouting for the other 29 teams around the league with our assistant coaches, something that SB Nation's Paul Flannery witnessed when he spent a day with the assistant coach.
Get well soon, Steve. "All that other stuff will go out the window when it's time to coach".