Griner, 31, has now been held in Russian custody for 130 days — an ordeal that began one week before Russia invaded Ukraine.
Her detention repeatedly has been extended, and her request for home detention was denied.
No U.S. Embassy officials were present for Monday's hearing.
A representative for the U.S. Embassy told NPR that it was informed the session was a "closed administrative meeting" and Embassy staff would not be allowed to attend.
"It was a technical hearing involving the prolongation of the arrest," Boikov said of the session. "Not more than that."
The U.S. Embassy says American officials plan to attend the formal trial when hearings finally begin.
Griner was arrested on Feb. 17, after authorities at a Moscow area airport allegedly found cannabis vape cartridges in her luggage
prompting a criminal charge of smuggling drugs into Russia. She could face up to 10 years in prison if she's convicted.