Why is Visual Studio Application Timelines not working?

I'm trying to analyse performance of a WPF application using the Visual Studio 2015 Application Timeline tool. However, when I attempt to start the profiler, I receive the following error message:

Diagnostics session failed to start.

Failed to start trace session (0x00000005).

I've tried:

• running as a privileged user.
• a smaller toy WPF project.
• checking event log for clues.
• googling :)

No idea where to go next. Has anyone seen this issue before?