miss a beat

not miss a beat

To not slow down, pause, or lose one's place, especially in spite of a potential distraction or disruption. The boss didn't miss a beat during the meeting when his son-in-law walked in 45 minutes late. You can't fluster my mother. No matter how you try to shock or annoy her, she never misses a beat.
See also: beat, miss, not
Farlex Dictionary of Idioms.

miss a beat

Hesitate momentarily, out of embarrassment or confusion. This expression is most often used in a negative context, as in He sidestepped the reporter's probe into his personal life without missing a beat, or Not missing a beat, she outlined all the reasons for her decision. This expression alludes to the regular beat of musical time. [Mid-1900s]
See also: beat, miss
The American Heritage® Dictionary of Idioms by Christine Ammer.

miss a beat

hesitate or falter, especially in demanding circumstances or when making a transition from one activity to another.
See also: beat, miss
Farlex Partner Idioms Dictionary
See also:
  • not miss a beat
  • not skip a beat
  • skip a beat
  • without skipping a beat
  • without missing a beat
  • get on with (something)
  • get on with it
  • recollect
  • re-collect
  • recollect (oneself)