Ia m sorry in advance as it's somewhat difficult for me to describe the bug that I am seeing  because I have the same code working on multiple platforms. I can provide a github link where code can be tested . I will do my best to be clear and provide code examples where the Music portion for android will fail.

Ok I have noticed some weird behaviour which only leads me to believe that Music connected functions don't function properly in Android. I cannot quite put my finger on it because ,  I noticed that as a solution I can play a wav as a sound effect , but as I try to use the music_mixer, the function returns null.

I will provide some code examples to prove a point . I have a few projects that work fine on multiple platforms but once in Android I have to convert Mix_Music to a Mix_Chunk. In another code base , I noticed that Mix_LoadMUS_RW always returns null.



/* Code Sample 1------------------------------*/


                Mix_Music *music;
                SDL_RWops *musicRw;
                char *musicBuffer;

		sound_create_primary_buffer(sgpMusicTrack);
		if (!success) {
			sgpMusicTrack = NULL;
		} else {
			int bytestoread = SFileGetFileSize(sgpMusicTrack, 0);
			musicBuffer = (char *)MusicAllocPtr(bytestoread);
			SFileReadFile(sgpMusicTrack, musicBuffer, bytestoread, NULL, 0);

			musicRw = SDL_RWFromConstMem(musicBuffer, bytestoread);
			if (musicRw == NULL) {
				SDL_Log(SDL_GetError());
			}
			music = Mix_LoadMUS_RW(musicRw, 1); // This function always returns null despite musicRw always having a pointer
			Mix_VolumeMusic(MIX_MAX_VOLUME - MIX_MAX_VOLUME * sglMusicVolume / VOLUME_MIN);
			Mix_PlayMusic(music, -1);// this will never play because there is no music loaded in the mixer.

			sgnMusicTrack = nTrack;





/*CODE SAMPLE2----------------------------------------------------------------*/


#include <SDL.h>
#include <SDL_image.h>
#include <SDL_mixer.h>
#include <stdio.h>
#include <android/log.h>

#include <iostream>
#include <fstream>


Mix_Music *gMusic = NULL;
Mix_Chunk *gHigh = NULL;




int main(int /*argc*/, char* /*argv*/[]) {

    bool success = true;
    SDL_Window *window;                    // Declare a pointer

    SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO);              // Initialize SDL2

    // Create an application window with the following settings:
    window = SDL_CreateWindow(
            "An SDL2 window",                  // window title
            SDL_WINDOWPOS_UNDEFINED,           // initial x position
            SDL_WINDOWPOS_UNDEFINED,           // initial y position
            640,                               // width, in pixels
            480,                               // height, in pixels
            SDL_WINDOW_OPENGL                  // flags - see below
    );

    // Check that the window was successfully created
    if (window == NULL) {
        // In the case that the window could not be made...
        printf("Could not create window: %s\n", SDL_GetError());
        return 1;
    }

    // The window is open: could enter program loop here (see SDL_PollEvent())
    // Setup renderer
    SDL_Renderer *renderer = NULL;
    renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

    // Set render color to red ( background will be rendered in this color )
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);

    // Clear winow
    SDL_RenderClear(renderer);




    if( Mix_OpenAudio( 44100, MIX_DEFAULT_FORMAT, 2, 2048 ) < 0 )
    {
        __android_log_print(ANDROID_LOG_VERBOSE, "DEBUGSOUND", Mix_GetError(), 1);
        success = false;
    }
//THIS FAILS
    gMusic = Mix_LoadMUS("/sdcard/music/test.wav");///// THIS FAILS
    if (gMusic == NULL) {
        //char * error  [100] = {0};
        //sprintf(error,Mix_GetError())
        printf("Failed to load beat music! SDL_mixer Error: %s\n", Mix_GetError());
        __android_log_print(ANDROID_LOG_VERBOSE, "DEBUGSOUND", Mix_GetError(), 1);

        success = false;
    }

//THIS Succeeds! 
    gHigh = Mix_LoadWAV( "/sdcard/music/test.wav" );
    if( gHigh == NULL )
    {
        printf( "Failed to load high sound effect! SDL_mixer Error: %s\n", Mix_GetError() );
        __android_log_print(ANDROID_LOG_VERBOSE, "DEBUGSOUND", Mix_GetError(), 1);
        success = false;
    }


    // bouyatest

    // Creat a rect at pos ( 50, 50 ) that's 50 pixels wide and 50 pixels high.
    SDL_Rect r;
    r.x = 50;
    r.y = 50;
    r.w = 500;
    r.h = 500;

    // Set render color to blue ( rect will be rendered in this color )
    SDL_SetRenderDrawColor( renderer, 0, 0, 255, 255 );

    // Render image
    SDL_Surface *loadedImage = IMG_Load("res/hello.png");
    SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, loadedImage);
    SDL_FreeSurface(loadedImage);

    SDL_RenderCopy(renderer, texture, NULL, &r);

    // Render the rect to the screen
    SDL_RenderPresent(renderer);

    bool quit = false;

                        //Event handler
    SDL_Event e;

                        //While application is running
     while( !quit )
     {
                                //Handle events on queue
     while( SDL_PollEvent( &e ) != 0 )
     {
                                        //User requests quit
    if( e.type == SDL_QUIT )
    {
       quit = true;
    }
                                        //Handle key press
    else if( e.type == SDL_MOUSEBUTTONDOWN )
    {

    if( Mix_PlayingMusic() == 0 )
     {
                                                                //Play the music
         Mix_PlayChannel( -1, gHigh, 0 );
     }

    }

         }
}
                                     

    SDL_Delay(8000);  // Pause execution for 3000 milliseconds, for example

    // Close and destroy the window
    SDL_DestroyWindow(window);

    // Clean up
    SDL_Quit();
    return 0;
}