App Not Working Properly on Android P Devices

Recently, I tested my app on some devices (Nougat and Oreo) and it worked fine. But on Android P devices, I am not able to login into the home screen. My compile & target sdk versions are 28.

I am using activeandroid orm for db and fast android networking library for making http requests. I have enabled crash reporting but didnt get any log info as the app was not crashing.

Is there any way to determine why the user is unable to login?

This is the code for Login:

public class LoginActivity extends AppCompatActivity implements View.OnClickListener {

private static final String TAG = LoginActivity.class.getSimpleName();

private EditText etUsername, etPwd;
private TextView forgotTV;
private Button loginBtn;
private Coach coach;
private String username, pwd, coach_id;

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

    init();

    forgotTV.setOnClickListener(this);
    loginBtn.setOnClickListener(this);

}

private void init() {
    etPwd = findViewById(R.id.etPwd);
    etUsername = findViewById(R.id.etUsername);
    forgotTV = findViewById(R.id.forgotTV);
    loginBtn = findViewById(R.id.loginBtn);
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.loginBtn:
            // add validation later;
            username = etUsername.getText().toString();
            pwd = etPwd.getText().toString();
            doLogin(username, pwd);
            break;
        case R.id.forgotTV:
            Snackbar.make(findViewById(android.R.id.content), "Coming Soon", Snackbar.LENGTH_LONG).show();
            break;
    }
}

private void doLogin(String email, String pwd) {

    JSONObject jsonObject = new JSONObject();
    try {
        jsonObject.put("username", "testcoach@gmail.com");
        jsonObject.put("password", "123@abcd");
    } catch (JSONException e) {
        e.printStackTrace();
    }

    AndroidNetworking.post(Constants.LOGIN_COACH)
            .addJSONObjectBody(jsonObject)
            .setTag("Coach Login")
            .setPriority(Priority.HIGH)
            .build()
            .getAsJSONObject(new JSONObjectRequestListener() {
                @Override
                public void onResponse(JSONObject response) {
                    if (response != null) {

                        Log.d(TAG, "Login Resp:\t" + response.toString());

                        try {
                            JSONObject object = new JSONObject(response.toString());
                            JSONObject details = object.getJSONObject("coach_details");

                            coach_id = details.getString("coach_id");

                            String academyId = details.getString("academy_id");
                            String username = details.getString("username");
                            String firstName = details.getString("first_name");
                            String lastName = details.getString("last_name");
                            String midName = details.getString("middle_name");
                            String nick = details.getString("nick_name");
                            String gender = details.getString("gender");
                            String mobile = details.getString("mobile");
                            String state = details.getString("state");
                            String email_coach = details.getString("email");

                            // Save in db
                            saveCoachDetails(coach_id, academyId, username, firstName, lastName, midName, nick, gender, mobile, state, email_coach);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                }

                @Override
                public void onError(ANError anError) {

                }
            });
}

private void saveCoachDetails(String idCoach, String academyId, String username, String firstName, String lastName, String midName, String nick, String gender, String mobile, String state, String email) {

    coach = new Coach();
    coach.setCoachId(idCoach);
    coach.setAcademyId(academyId);
    coach.setUsername(username);
    coach.setEmailAddr(email);
    coach.setFirstName(firstName);
    coach.setLastName(lastName);
    coach.setMidName(midName);
    coach.setNickName(nick);
    coach.setGender(gender);
    coach.setMobileNum(mobile);
    coach.setOriginState(state);

    coach.save();

    Coach coachQuery = new Select()
            .from(Coach.class)
            .where("coach_id=?", coach_id)
            .executeSingle();
    Log.d(TAG, "Coach id:\t" + coachQuery.coachId);
    coach_id = coachQuery.coachId;

    getAllData(coach_id);


}

private void getAllData(String coach_id) {

    Log.d(TAG, "Getting Data");

    JSONObject data = new JSONObject();
    try {
        data.put("coach_id", coach_id);
    } catch (JSONException e) {
        e.printStackTrace();
    }

    AndroidNetworking.post(Constants.GET_ALL_DATA)
            .setTag("Get Coach Meta")
            .setPriority(Priority.HIGH)
            .addJSONObjectBody(data)
            .build()
            .getAsJSONObject(new JSONObjectRequestListener() {
                @Override
                public void onResponse(JSONObject response) {
                    if (response != null){
                        Log.d(TAG, "GAD:\t" + response.toString());
                        startActivity(new Intent(LoginActivity.this, MainActivity.class));
                    }
                }

                @Override
                public void onError(ANError anError) {
                    Log.d(TAG, anError.getErrorDetail());
                }
            });

}

}

at the moment it's hard coded only cos it's a test apk and not the final one. Can anyone please test this code on android 9.0 OS devices and check if you are able to go to next activity or not. Thanks