A code viewer tab does not open on Windows 7

Pre-requirements: OS Windows 7 or Windows Server 2008 R2 with the latest updates and .NET Framework 4.7.1 installed.

Problem: You drill down into an assembly to view the code. dotPeek shows "decompiling" progress bar but nothing happens after it has finished, no text editor (code viewer tab) opens. 

Solution: A list of solutions can be found in this thread