It’s 5.1 DTS HD master audio. All 4k movies DO NOT have atmos mixes, by the way. That is entirely false. Some come with the same audio as a previous blu ray mix. Universal tends to use DTS X, which is also great. Sometimes the studio just doesn’t want to spend the money to mix it in atmos, especially if it wasn’t Dolby atmos on the theatrical release. It’s on a case by case basis.