How to add an external library to a Qt project in Qt Creator

Question

Qt Creator my_project -> Right Click -> Add Library no longer works. It was working before, with an earlier Qt version (5.8.0), and I had even added a few libraries, but for some reason it just doesn't show the Add Library window anymore. It's like that tab (Add Library) is deactivated/ inactive.

What could be the issue?

Thank you all in advance.

Qt Creator 4.3.1
Based on Qt 5.9.0 (GCC 5.3.1 20160406 (Red Hat 5.3.1-6), 64 bit)
Built on May 28 2017 14:10:10
From revision bfd818b2b1
Copyright 2008-2017 The Qt Company Ltd. All rights reserved.
The program is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Answer 1

This is a regression bug from QtCreator 4.3. There has been a bug report filed here: https://bugreports.qt.io/browse/QTCREATORBUG-18263