I am also experiencing this issue. It has driven me crazy since I started a brand new project and thought something got messed up in my Blueprints. So I rebuilt them one by one and checked each Blueprint with several starts and closes of the editor.
As far as I can tell for now, it’s always happening if you open an UMG Editor window during your work in the Unreal Editor 4.11. There are also some warnings present:
At editor start up:
Warning: No registered external profiler was matched with a command-line switch (or the DLL could not be loaded). External profiling features will not be available.
Each time an UMG Editor gets opened or closed
Warning: Cannot spawn tab because no spawner is registered for ‘BlueprintProfiler’