I just installed Google Assistant on my Raspberry Pi 3B as part of a Magic Mirror project I've been working off and on for the past year or so. I can run the assistant fine, except when it responds the first little bit of the response is cut off.
For example I would ask "What time is it" (The time being 10:30 PM for example) and it would respond "30 PM." Additionally whenever this happens the screen will cut out for just the blink of an eye. Not 100% sure these are related but it feels like more than a coincidence to me.
Any help with this little hiccup would be much appreciated!
In addition to the comments, there may be some configuration needed for the HDMI to behave as desired.
Please see the Audio Configuration documents for more ideas.