Symptom
When connecting a TRAKTOR KONTROL S4 MK3 to a running computer, you can no longer use its channels in standalone mixer mode.
Cause
The technical setup of the S4 MK3 does not allow it to be used as a hybrid standalone mixer in conjunction with TRAKTOR.
Solution
You can either use your S4 MK3 entirely in standalone mixer mode or use it with the TRAKTOR PRO 3 software. While using it with TRAKTOR PRO 3, external audio players need to be used as Live Input in TRAKTOR.