I had issues with 48k audio too (crackling). The same issues that were reported in this question: https://answers.unrealengine.com/questions/593219/android-new-audiomixerandroid-in-416p1-results-cra.html
In my case I was using 48k audio wavs from one of the asset collections, after some discussion with the author we tried 44k and that worked fine on both 4.16 and 4.17. I’m not sure if its because of Android itself (on this site, it says up to 44k is supported for wav Supported media formats | Android Developers) or some other UE thing…