Why In the Debug>Windows>Threads I see only 1 thread

may be it shows only managed threads, and there are more native threads going on. To view native threads check Enable native code debugging in your main project settings and start a new debugging session.

 

Warning: it can take a bit of time to load symbols for all those native DLLs on the first run

 

Remember to uncheck this option once you are done having fun with that.