"OK Google" doesn't beep/prompt anymore?

As of today, I noticed that when I say "OK Google" or touch the microphone, I don't get the audible "beep" that tells me it's ok to start speaking?

Has anyone else noticed this?

I uninstalled the latest version and tried it and the beep work, but when I updated again to the latest version, Sept 14th release, it doesn't beep for me.

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