Cannot paste external text to kivy window (Python)

I'm starting to learn Kivy to make GUIs and all is fine, but I can't paste external text to my TextInput widgets. There is no problem with copying and pasting text internal to the kivy window (copy from a TextInput to another). The issue is that I cannot paste text external to the kivy window (copy text from say the browser and paste it into a TextInput). My OS: Kali Linux Rolling 2020.1 (Debian) Here is some of my code

class LoginPage(Screen):

    keep_logged_var = BooleanProperty() # declaring some variables to use in the .kv file
    school_code_var = StringProperty()
    user_id_var = StringProperty()
    password_var = StringProperty()
    failed_var = BooleanProperty()


    def __init__(self, **kwargs):
        super(LoginPage, self).__init__(**kwargs)

        self.keep_logged_var = keep_logged # assigning value to my variables
        if self.keep_logged_var:
            self.school_code_var = school_code
            self.user_id_var = user_id
            self.password_var = password
        self.failed_var = False


    def login(self, keep_logged, school_code_, user_id_, password_):
        if keep_logged == 'normal': keep_logged = False
        elif keep_logged == 'down': keep_logged = True

        global token, school_code, user_id, password
        school_code = school_code_
        user_id = user_id_
        password = password_
        token = get_token(school_code, user_id, password)

        if token == 'Failed to log in': # login failed
            print('failed')
            self.failed_var = True
        else: # login successful
            if keep_logged:
                settings['keep_logged'] = True
                settings['school_code'] = school_code
                settings['user_id'] = user_id
                settings['password'] = password
                with open('settings.json', 'w') as file:
                    json.dump(settings, file, indent=2)

            global scheda
            scheda = get_schede()

and here is my kivy file

<LoginPage>:

    keep_logged: root.keep_logged_var
    school_code: root.school_code_var
    user_id: root.user_id_var
    password: root.password_var
    failed: root.failed_var


    name: 'loginpage' # name of the window


    FloatLayout:

        canvas:
            Color:
                rgba: 1,1,1,1
            Rectangle:
                size: root.width, root.height

        Label: # school code label
            text: 'School Code: '
            font_size: 20
            pos_hint: {'x': -0.15, 'y':0.2}
            color: 0,0,0,1

        TextInput: # school code entry
            id: school_code_id
            text: root.school_code if root.keep_logged else ''
            multiline: False
            size_hint: 0.2, 0.05
            pos_hint: {'x': 0.45, 'y': 0.67}


        Label: # user id label
            text: 'User ID '
            font_size: 20
            pos_hint: {'x': -0.15, 'y': 0.1}
            color: 0,0,0,1

        TextInput: # user id entry
            id: user_id_id
            size_hint: 0.2, 0.05
            pos_hint: {'x': 0.45, 'y': 0.57}
            multiline: False
            text: root.user_id if root.keep_logged else ''


        Label: # password label
            text: 'Password '
            font_size: 20
            pos_hint: {'x': -0.15, 'y': 0}
            color: 0,0,0,1


        TextInput: # password entry
            id: password_id
            size_hint: 0.2, 0.05
            pos_hint: {'x': 0.45, 'y': 0.47}
            password: True
            multiline: False
            text: root.password if root.keep_logged else ''


        CheckBox: # keep me logged in
            id: keep_logged_id
            size_hint: 0.4, 0.1
            background_color: 1,1,1,1
            color: 0,0,0,1
            pos_hint: {'x': 0.05, 'y': 0.33}
            active: root.keep_logged_var

        Label: # keep me logged in
            text: 'Keep me logged in'
            color: 0,0,0,1
            font_size: 15
            pos_hint: {'x': -0.14, 'y': -0.12}


        Button: # login button
            text: 'Login'
            size_hint: 0.13, 0.06
            color: 1,1,1,1
            pos_hint: {'x': 0.5, 'y': 0.35}
            on_press:
                root.login(keep_logged_id.state, school_code_id.text, user_id_id.text, password_id.text)


        Label: # failed login label
            text: 'Login failed' if root.failed else ''
            font_size: 20
            pos_hint: {'y': -0.2}
            color: 1,0,0,1

Thanks for your help

Solved: I was missing some required modules that didn't come with my os (xclip and xsel) after installing them sudo apt install xclip sudo apt install xsel I was able to copy/paste successfully from and to my kivy TextInput.