A failure by the garnishee to comply with lawful process might result in contempt citations or, if allowed under local law, disgorgement of funds that ought to have been paid in on the garnishment.
The court will use its powers to work its way to the human being who signed off on thwarting the garnishment. That person will wind up coming to court, voluntarily or involuntarily. The money will wind up flowing from the employer to the creditor. Voluntarily or involuntarily.