What Causes Motors to Twitch When Quad is Armed?

If the power to start your motor (an ESC setting) is too low, they would twitch. Similarly if the idle speed (in betaflight) is too low they would also twitch. Increase either.

Did you configure the ESCs yourself or update their FW? If so see this page:

Where’s that located in betaflight

It’s a Pavo 20 pro nightfire. I loaded factory software back on, motors receive the correct beeps.