ViewPager2 onBindViewHolder funktioniert nicht richtig

public class AudioFilePanel extends AppCompatActivity
{
    public static final int FILE_BROWSER_REQUEST_CODE = 1;
    private String currentTab;
    private ViewPagerAdapter adapter;
    private ViewPager2 viewPager;
    private Map<String, List<FileElement>> content;


    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_audio_file_panel);


        viewPager = findViewById(R.id.view_pager2);
        TabLayout tabLayout = findViewById(R.id.tabs);
        Button addFilesByTag = findViewById(R.id.add_files_with_tag);


        if (null == currentTab)
        {
            currentTab = "music";
        }


        content = listByTag();


        adapter = new ViewPagerAdapter(getApplicationContext(), new ArrayList<>(content.values()), currentTab);
        viewPager.setAdapter(adapter);
        new TabLayoutMediator(tabLayout, viewPager,
            (tab, position) -> tab.setText(content.keySet().toArray()[position].toString())).attach();


        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
        {
            @Override
            public void onTabSelected(TabLayout.Tab tab)
            {
                currentTab = tab.getText().toString();
            }


            @Override
            public void onTabUnselected(TabLayout.Tab tab)
            {
            }


            @Override
            public void onTabReselected(TabLayout.Tab tab)
            {
            }
        });
        addFilesByTag.setOnClickListener(l ->
        {
            Intent fileBrowser = new Intent(AudioFilePanel.this, FileBrowser.class);
            startActivityForResult(fileBrowser, 1);
        });
    }


    private void updateViweData()
    {
        content = listByTag();
        adapter = new ViewPagerAdapter(getApplicationContext(), new ArrayList<>(content.values()), currentTab);
        viewPager.setAdapter(adapter);
    }


    private Map<String, List<FileElement>> listByTag()
    {
        Map<String, List<FileElement>> result = new HashMap<>();
        DirectoryDao dao = new DirectoryDao(getApplicationContext());
        String[] categories = {"music", "ambience", "effect"};


        for (String category : categories)
        {
            List<FileElement> directories =
                dao.getDirectoriesForCategory(category).stream().map(f -> new FileElement( new File(f.getPath()).getName(), f.getPath(), true)).collect(Collectors.toList());
            result.put(category, directories);
        }
        return result;
    }


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK && requestCode == FILE_BROWSER_REQUEST_CODE)
        {
            String path = data.getStringExtra("path");
            storeDirectory(path, data.getBooleanExtra("includeSubdirs", true), currentTab);
            updateViweData();
        }
    }


    private void storeDirectory(String path, boolean recursive, String tag)
    {
        Directory directory = new Directory();
        directory.setPath(path);
        directory.setTag(tag);
        directory.setRecursive(recursive);
        DirectoryDao dao = new DirectoryDao(getApplicationContext());
        directory.setId(dao.insert(directory));
    }
}

public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewHolder>
{


    private static final String PREVIOUS_DIRECTORY = "previous directory";
    private List<List<FileElement>> filesListsByCategory;
    private LayoutInflater mInflater;
    private Context ctx;
    private ItemListAdapter adapter;
    private String rootPath;
    private List<FileElement> rootElements;
    private String tag;


    public ViewPagerAdapter(Context context, List<List<FileElement>> data, String tag)
    {
        this.mInflater = LayoutInflater.from(context);
        this.filesListsByCategory = data;
        this.ctx = context;
        this.tag = tag;
        rootElements = new ArrayList<>(filesListsByCategory.get(0));
    }


    @NotNull
    @Override
    public ViewHolder onCreateViewHolder(@NotNull ViewGroup parent, int viewType)
    {
        return new ViewHolder(mInflater.inflate(R.layout.item_viewpager, parent, false));
    }


    @Override
    public void onBindViewHolder(ViewHolder holder, int position)
    {
        FileBrowserService fbs = new FileBrowserService();
        List<FileElement> categoryFiles = new ArrayList<>(filesListsByCategory.get(position));


        adapter = new ItemListAdapter(categoryFiles, item -> handleClickOnElement(fbs, item));
        holder.myView.setAdapter(adapter);
    }


    private void handleClickOnElement(FileBrowserService fbs, FileElement item)
    {
        if (new File(item.getPath()).isDirectory())
        {
            List<FileElement> newContent;
            String newPath;
            if (item.isRoot())
            {
                rootPath = item.getPath();
            }


            if (PREVIOUS_DIRECTORY.equals(item.getName()))
            {
                newPath = item.getPath().substring(0, item.getPath().lastIndexOf('/'));
            } else
            {
                newPath = item.getPath();
            }
            FileElement goToParent = new FileElement(PREVIOUS_DIRECTORY, newPath, false);


            if (item.getPath().equals(rootPath) && !item.isRoot())
            {
                newContent = rootElements;
            } else
            {
                newContent = fbs.getFiles(newPath);
                newContent.add(0, goToParent);
            }
            updateListElements(newContent);
        } else
        {
            //TODO: play track
        }
    }


    private void updateListElements(List<FileElement> newContent)
    {
        adapter.updateData(null, "clearData");
        adapter.updateData(newContent, "updateData");
    }


    @Override
    public int getItemCount()
    {
        return filesListsByCategory.size();
    }


    class ViewHolder extends RecyclerView.ViewHolder
    {
        RecyclerView myView;
        RelativeLayout relativeLayout;


        ViewHolder(View itemView)
        {
            super(itemView);


            myView = itemView.findViewById(R.id.my_list);
            myView.setLayoutManager(new LinearLayoutManager(ctx));
            relativeLayout = itemView.findViewById(R.id.container);
        }
    }
}