PermissionHandler callbacks are never called for separate process

[LockdownX7]

My app runs a service on a separate process, defined in the manifest as such:

<service
	android:name=".ManagerService"
	android:process=":ManagerProcess"/>

This service requires permissions on certain user actions, and I'm requesting them in the following way:

String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.RECORD_AUDIO, Manifest.permission.CAMERA};
Permissions.Options options = new Permissions.Options()
	.setRationaleDialogTitle("test rationale")
	.setSettingsDialogTitle("test title")
	.setSettingsDialogMessage("test settings")
	.setSettingsText(context.getString(R.string.action_settings))
	.setCreateNewTask(true);    //Needs to create a task because we're asking for permissions outside of activity context
final String rationale = "placeholder";
Permissions.check(context, permissions, rationale, options, new PermissionHandler() {
	@Override
	public void onGranted() {
		//TODO
		Log.d("test4636", "granted");
		Toast.makeText(context, "granted", Toast.LENGTH_LONG).show();
	}

	@Override
	public void onDenied(Context context, ArrayList<String> deniedPermissions) {
		//TODO
		Log.d("test4636", "denied");
		Toast.makeText(context, "denied", Toast.LENGTH_LONG).show();
		for (String perm : deniedPermissions) {
			Log.d("test4636", perm);
		}
	}
});

With this setup, onGranted() and onDenied() are never called. Removing android:process=":ManagerProcess" from the service solves the issue, but I can't implement it that way because the service has to be running on a separate process due to other requirements. Is there any workaround to getting the callbacks to work when using android:process?