CLONE - lupdate cannot resolve context when member function implementaton is in a namespace scope

This is a clone of https://bugreports.qt.io/browse/QTVSADDINBUG-281 since the original issue still persists with Qt VS Add-In 2.3.3 and Visual Studio 2019.

The bug happens when using tr() inside a namespace and the source and header files are located in different directories.

I attached a Visual Studio project showing the problem.

In the attached project lupdate reports

C:/Temporary/LUpdateTest/src/LUpdateTest/LUpdateTest.cpp:11: Qualifying with unknown namespace/class ::LUpdateTest

for the following source (LUpdateTest.cpp):

 
#include "LUpdateTest.h"

namespace Namespace
{

LUpdateTest::LUpdateTest(QWidget *parent)
	: QDialog(parent)
{
	ui.setupUi(this);
	ui.label->setText(tr("Translation here"));
}

}

lupdate_de.ts contains

<context>
  <name>LUpdateTest</name>
  <message>
    <location filename="../../src/LUpdateTest/LUpdateTest.cpp" line="11"/>
    <source>Translation here</source>
    <translation>Übersetzung hier</translation>
  </message>
</context>

The name tag contains "LUpdateTest" but it should be "Namespace::LUpdateTest".