Steps to reproduce:

1. Create new project
2. Build and run standalone as development build (run it as windowed for an easier repro)
3. Back in editor, connect profiler to the build
4. Click back on build to confirm that profiler got connected
5. Click back on profiler and sometimes you'll get an indication of something loading and after that profiler will get disconnected

So far, the best way to repro this is by enabling/disabling profiler options (Scripts, Rendering, GarbageCollector etc.)

Tested on OSX

Reproduced with: 5.4.0p4, 5.4.4f1, 5.5.0f3, 5.5.0p3, 5.6.0b3
Not reproducible: 5.3.7p3