I use the assistants with a Plantronics headset. After the last update, the phone asked me whether I'd like too complete a voice dialing request using Bixby or Assistant.
OOI I selected Bixby. Now nothing happens when I ask the phone to dial and I have yet to figure out how to reset to Assistant!
Note - to be more accurate, when I press the button on the headset that used to launch Google as the Virtual Assistant, it now does nothing. There must be a menu item somewhere in the phone to reset the choice from Bixby to Google but I can't find it!