UPDATE The supposed duplicate is a question on being stucking in \"Waiting For Debugger\" when executing Run, while this
For me Run->Attach debugger to Android process was working, but I had to do it every time app was launched.
Fix: There may be a problem with your 'App launch configuration'(To verify this create new project to see if it's working fine). Just delete app configuration, open MainActivity file and Run->Debug (new conffiguration will be created)