Sampler Cue button

I just bought the DDJ-FLX4 and am experiencing some problems and would appreciate any help: Sampler Cue Issue: When I activate the “cue” button for the sampler to preview the sample track in my headphones, it doesn’t work. Instead, the sound plays through both the master output and headphones if I turn up the sampler volume. Master Cue Issue: Having the same issue with the master cue button as well.

I use Rekordbox app on Android via USB-C cable