We have noticed that quickly double-clicking on tracks causes some to keep playing:

https://support.mixo.dj/t/double-clicking-on-tracks-causes-them-to-overlap

Is this the same issue you are having or are you just clicking on one track and that one alone won't turn off?

Double check our minimum requirements here to make sure your device works with MIXO:

https://support.mixo.dj/guide/mixo-system-requirements