FireFight Custom Challenges not counting across different game types?

I set up four custom challenges:

100 Grunt Infantry
70 Grunt Heroes
130 Grunt Specialists
310 Headshots

I went into one game of FF Doubles to get the Overlook DC in one go.

Toward the above challenges, I got:

20
20
32
0

Then I played three games of Gruntpocalypse

Despite getting more than enough Grunts in each category, my Custom Challenges now say:

20 ( even though I got more than 100 )
20 ( even though I got more than 70 )
32 ( even though I got more than 130 )
340

Is it because I already had a number other than 0 in a different game type ( FF Doubles vs Score Attack )?

Is this a known issue?

There’s definitely an issue with the Kill count it does as I’ve found that a few kills are missed off too.

On a Fire Fight Thursday I added 360 Kills in FireFight to my Custom Challenges and played 3 games killing everyone (it’s about 370 kils depending on the game), however the Custom Challenge said I’d killed 358.

Really annoying!