Try to takkle down export dir issues

src/main/java/de/dennisguse/opentracks/settings/ImportExportSettingsFragment.java

@@ -66,7 +66,11 @@ public class ImportExportSettingsFragment extends PreferenceFragmentCompat {
         instantExportDirectoryPreference.setSummaryProvider(preference -> {
             DocumentFile directory = PreferencesUtils.getDefaultExportDirectoryUri(getContext());
             //Use same value for not set as Androidx ListPreference and EditTextPreference
-            return directory != null ? directory.getName() : getString(R.string.not_set);
+            if (directory == null) {
+                return getString(R.string.not_set);
+            }
+
+            return directory.getUri().toString() + (directory.canWrite() ? "" : getString(R.string.export_dir_not_writable));
         });
     }
 }

src/main/java/de/dennisguse/opentracks/settings/PreferencesUtils.java

@@ -531,12 +531,12 @@ public class PreferencesUtils {
     }
 
     public static DocumentFile getDefaultExportDirectoryUri(Context context) {
-        String singleExportDirectorySettingsKey = getString(R.string.settings_default_export_directory_key, null);
-        if (singleExportDirectorySettingsKey == null) {
+        String singleExportDirectory = getString(R.string.settings_default_export_directory_key, null);
+        if (singleExportDirectory == null) {
             return null;
         }
         try {
-            return DocumentFile.fromTreeUri(context, Uri.parse(singleExportDirectorySettingsKey));
+            return DocumentFile.fromTreeUri(context, Uri.parse(singleExportDirectory));
         } catch (Exception e) {
             Log.w(TAG, "Could not decode default export directory: " + e.getMessage());
         }