@wrknight: Are you using Google Assistant, or Bixby, and are you connected to Wi-Fi or Mobile Data? If you head to Settings > General Management > Keyboard List and Default, are Google Voice Typing and Samsung Voice Input both activated?
What can I say? Today, it is working. Yesterday it wasn't. I tried, my daughter tried, my wife tried, and it refused to work for any of us. When we activated the microphone on the keyboard and spoke into the phone, the blue microphone icon "pulsated" like it was responding to the voice input, but no text came out. Today, after a nice night's sleep, it wants to play nice. Perhaps I said something that hurt its feelings
To the best of my knowledge, I haven't changed a thing. However, it seems to be terribly sensitive and I worry about touching anything or even passing gas too near it.
In answer to your questions, I have never used Google Assistant or Bixby and I have done nothing that I know of to change the settings that came with the phone. It is brand new directly from Samsung. It was unlocked and a couple of days ago I set it up with T-Mobile. In the process, they copied all the data and apps from my Galaxy S7 to this one.
The phone is set up to use wifi whenever it's available and automatically switch to mobile when wifi isn't available.
Under Settings>General Management>Keyboard List and Default, Google voice typing, Samsung voice input and Keyboard button on navigation bar are all activated. Samsung keyboard is set to English.
If you have any recommendations for improving my settings, I would appreciate knowing them.