Trouble showing datepicker dialog fragment using Navigation component

I am trying to use the Navigation Component to show a date picker dialog fragment. I am getting the following error:

android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?

This is my DatePicker class

class DatePickerFragment : DialogFragment(), DatePickerDialog.OnDateSetListener {

var datePickerListener: DatePickerFragmentListener? = null

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
    // Use the current date as the default date in the picker
    val c = Calendar.getInstance()
    val year = c.get(Calendar.YEAR)
    val month = c.get(Calendar.MONTH)
    val day = c.get(Calendar.DAY_OF_MONTH)

    // Create a new instance of DatePickerDialog and return it
    return DatePickerDialog(VitrixDataCollectionApp.context, this, year, month, day)
}

interface DatePickerFragmentListener {
    fun onDateSet(view: DatePicker, year: Int, month: Int, day: Int)
}

override fun onDateSet(view: DatePicker, year: Int, month: Int, day: Int) {
    datePickerListener?.onDateSet(view,year, month, day)
}
}

I would like to show the date picker when a TextInputField has focus. Here is my code to Navigate to the DatePicker

private fun showDatePicker(hasFocus: Boolean, view: View) {
    Log.i(FRAGMENT_NAME, "Has focus $hasFocus")
    if (hasFocus) {
        Navigation.findNavController(view).navigate(R.id.action_createPatientDetailsFragment_to_datePickerFragment)
    }
}

Here are the relevant parts of my navigation graph xml

<fragment android:id="@+id/createPatientDetailsFragment"
          android:name="com.datacollection.ui.patients.create_patient.patient_details.CreatePatientDetailsFragment"
          android:label="create_patient_details_fragment"
          tools:layout="@layout/create_patient_details_fragment">
    <action android:id="@+id/action_createPatientDetailsFragment_to_datePickerFragment"
            app:destination="@id/datePickerFragment"/>
</fragment>
<dialog
        android:id="@+id/datePickerFragment"
        android:name="com.datacollection.ui.DatePickerFragment"/>

Here are my questions:

1. How do I get the dialog fragment to show?
2. How do I find the id of my DatePicker fragment, I sort of guessed it to be R.id.datePickerFragment

Let me know if you need any more info or need to see any more of my code.

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