The charges against Jennessee were dismissed without prejudice, which means they could be refiled in the future if circumstances change.
Jennessee's defense attorney, Cara Tangaro, said her client has maintained her innocence from the start of this case and "was not willing to resolve this case for anything less than a dismissal." Jennessee pleaded not guilty to all charges in February.
It was not explicitly clear whether the uncooperative witnesses were also the two 17-year-old victims in this case, but three months ago, the teens also balked at the prospect of testifying against their foster mother, Delshawn Renee Little.
Little, 32, is serving three years of strict probation during which she was ordered to stay away from all children, including her own.
Her probation began in April after she entered into a plea deal with prosecutors that spared her what could have been a life sentence. Little pleaded guilty to two counts of forcible sexual abuse, second-degree felonies each punishable by up to 15 years in prison.
At the time, prosecutors said the plea deal came about, in part, because the 17-year-old victims did not want to testify in open court before a judge or jury.
Jennessee and Little were arrested and charged in October.
According to charging documents, one of Little's foster sons told authorities he had sex with his foster mother on three occasions between June and September 2012 at their Kearns home.
The charges also allege that last July, Little asked the teen to film her and her boyfriend having sex.
On another occasion, the documents state, the teenager and his foster brother went into Little's bedroom, where they allegedly engaged in sex acts with Little and Jennessee.
Tangaro said Jennessee and Little were acquaintances at the time of the alleged crime, but denied Jennessee had any sexual contact with Little's teen foster sons.
"We were prepared for trial and felt that we would expose some huge weaknesses in the State's case," Tangaro said. "Millana is glad that this is over and wishes to move on with her life."