Here is one way to easily reproduce (it is not limited to this method, but this is the easiest I've found that "works" consistently):

1. Start punching and keep Fire button pressed
2. Press Vault button
3. Let go of Fire button

Result: Punching sounds will continue playing even if you stop punching and animation has stopped, sometimes for up to 20 seconds after you stopped punching.

Problem is that it acts more like a camera set to auto-exposure than it acts like eyes. As far as I know HDR = High Dynamic Range which means it should simulate more.. seeing more dynamic range. Which means sky shouldn't turn white when looking down at ground nor ground should turn super dark when looking at sky, it should keep contrast pretty even.

That being said, I have not exactly noticed when it happened, but it looks much better in recent alpha builds (at least for me, sky never turns white like it used to and ground doesn't lose as much detail), I assume they are actively working on it.

I have tested again and it is not random, read again/follow the steps I provided and see for yourself. Every other cases will play correct animation. I can make a video if needed.

It only happens with fists up + sprinting and is it not random. Hopefully this might help figuring out the cause, here is how to replicate:

1. Put your fists up and start sprinting
2. Press "vault" and don't stop sprinting during/after the vault
3. Press "vault" again without stopping sprinting
4. Repeat step 3 until satisfied

Result: First jump will ALWAYS be the "slow vault" animation. The next and consecutive jumps will ALWAYS be the "jump" animation.

Good luck!

PS: The slow vault animation looks great when player is walking with fists down, but when in "attack mode" the transition from "fighting" pose to vault animation and back to fighting pose looks very robotic because it goes to "idle" pose (fists down/straight spine) before starting the actual vault animation. And it is anti-climatic due to the length of the animation, player is in "attack" mode after all, he shouldn't look or be completely helpless for this long. Maybe you guys should consider doing a different animation for when players has its fists up that is slightly faster/more aggressive, that would start with the "fighting" pose instead of "idle" pose. It would look and feel much smoother.