stat.sprintOneCm stops counting after hitting a mob

Reproduce:

/scoreboard objectives add sprint stat.sprintOneCm
/scoreboard objectives setdisplay sidebar sprint

Hit a mob while running, be sure to hold sprint key, the score stops increasing after you hit it.

Press sprint.
Press forward.
Don't release sprint.
Hit mob.
You still sprint, but stat.sprintOneCm stops counting.