Intermittent loss of audio with new Contour box

Several times an evening and random times I lose audio watching live tv, movies, or recorded shows.  Picture is fine. Can restore audio by going backward & the playing live or recorded shows. Only happens on new Contour box, not two other mini boxes.  Reset box repeatedly, problem recurred Cox techs swapped out box, same problem.  Sound loss occurs on all 3 sound outputs from Contour box, so problem is in the Contour box.  Second Cox tech changed out cable from pole to house, & house to Contour box.  Same problems occurred.  "Escalated" tech could not solve, said maybe software problem wContour box. "Tech stated possible firm ware issue but the engineers are still working on it " basically answer we have no clue so please pay your high cost for inadequate quality system.Problem is very irritating.  Anyone else facing same issue?