After more than 10 months of jury selection and 100 days of trial across another half a year, the sprawling and much-delayed gang conspiracy case against the Atlanta rapper Young Thug and five associates has been halted indefinitely.

Judge Ural Glanville announced on Monday in a Fulton County, Ga., courtroom that the case would not proceed until another judge decides whether Judge Glanville should recuse himself from overseeing the trial. The surprise ruling followed weeks of disputes between the court and defense attorneys, who have argued that a meeting between the judge, prosecutors and an uncooperative witness was improper and potentially unconstitutional.

Judge Glanville had previously denied multiple motions from the defense that called for him to step aside, calling his actions regarding last month’s meeting and its aftermath proper. But on Monday, during a hearing about releasing a transcript of the secret meeting, he agreed that an outside judge should decide how the trial would proceed.

Jurors have not heard testimony in the case for two weeks amid the upheaval and were not expected to return until next Monday, following the July 4 holiday weekend. Asked by a prosecutor how long it would take for the trial to get back underway, Judge Glanville said the decision was no longer within his purview. “Hopefully it will get done fairly quickly,” he said.

Already plagued by disruptions and complications, both outside and inside the courtroom, the case hit its most recent snag beginning on June 7, when a key prosecution witness, Kenneth Copeland, refused to testify after being sworn in, invoking his Fifth Amendment right to protect against self-incrimination despite having already been granted immunity.

Mr. Copeland spent a weekend in jail on contempt charges and then agreed to testify, although he remained hard to pin down on basic factual matters. When Brian Steel, a lawyer for Young Thug, raised concerns about whether Mr. Copeland had been compelled to testify during a coercive meeting with Judge Glanville and prosecutors, the judge demanded to know how Mr. Steel learned of the closed-door meeting and then held him in contempt.

For refusing to reveal his source, Mr. Steel was sentenced to a maximum of 20 days in jail, to be served on the weekends, although the sentence was paused while Mr. Steel appeals the decision.

In a motion filed on Friday, Douglas S. Weinstein, a lawyer for another defendant in the case, argued that the judge’s secret meeting with a sworn witness and the judge’s refusal to step aside “offend public confidence in the independence, integrity and impartiality” of the case. He added, “An appearance of impropriety and bias hangs over the present trial due to Chief Judge Glanville’s failure to follow the law.”

Judge Glanville said on Monday that he would release the transcript of the private meeting with Mr. Copeland.

Young Thug, born Jeffery Williams, and 27 associates were initially charged in May 2022 under the Georgia state criminal racketeering law, or RICO, the same statute used to indict former President Donald J. Trump and others in what prosecutors called a conspiracy to overturn the 2020 election.

Prosecutors contend that Mr. Williams was a leader of YSL, or Young Slime Life, a subset of the national Bloods gang, and that he oversaw a criminal conspiracy to commit murder, attempted murder, armed robbery, witness intimidation and drug dealing.