Hello, I have the same problem, Siri hangs but after restart works, but once I put my MacBook Air into sleep mode and open again Siri hangs again and to use it I have to restart my MacBook. Where is the problem? I have over 1/4 free space on my SSD and good internet connection 40 mb/s. How to fix it permanently ? Jacob Update (08/24/2018): Fixed issue - power management and nvram reset helped.