Remnantmods

I have been trying to get a good score on "Stay Sharp" the target practice mission and I got 21.3 seconds for my lowest time with no civilians hit and then I scored 21.9 seconds and it gave me a new high score.
And whenever I get a lower time I don't get a new high score.

Does anyone know how the scoring works?
This is for co op.

It doesn't it's a fucking IW game

Hmm, weird.

Okay, turns out I failed.
My fastest time was 20.9 not 21.9.