I have tried all ways as far as I know to kick 10 times without touching the ground.
Normal kick, time stop kick, double jump between every kick
and I have tried different target: wolf man, lion man, flower, giant cannon morte, Abyssal Guardian...
I can be sure of kicking more than 10 times, even more than 20 times, but I still can't get this achievement.
Anyone have the same problem?

The achievement refers to the air kick you do once you have double jump by presin down (or diagonal down) + A in midair. You need to bounce of the enemy ten time without touching the ground.

I know and I fully understand and I have followed that instruction, I tried again and again, I even air kicked more than 20 times without touching ground, but I still can't get that achievement.
Now I even start to think about maybe that description means 100 times not just 10 times air kick.

I got the achievement after 10 kicks.

Me too. I nerfed my attack and stomped over 30 times on a dragon etc.; still nothing.
Many achievements don't get triggered in my playtrough (it sucks).
I recorded a macro for the backstep-achivement. Miriam backsteped for 3 hours; again nothing.
It tried it on PS4; first try. I guess the GOG-Version has some issues.

Why would you not use backstep for default way of moving around and record a macro to get an achievement?
Holy fug :0

I did, then I found out about the avhievement.
I asked myself, how often do I make a backstep to get the achievement?
My game/achievements are broken.
I finished the game (no boss achievement triggered)
Explored the map 100% (again no achievement triggered).

Looks like a couple of the quests are buggy. I'm at 89km or so on my playthrough, but the "Marathon" achievement didn't trigger. (That being said, the Kickstopper achievement triggered within seconds of me learning how to do the move... doing it in a place where you can't touch the ground probably didn't hurt).

I tried to get it with the dragon in the library.
It's a wide open space. I nerfed Miriam and kicked 48 times on the wings: Nothing!
I tried it under water: Again nothing!

I contacted the GOG-Support. They had a solution; but it didn't worked for me.
Maybe it helps you.

Please add the following files to the whitelist of your antivirus / firewall (also Windows Defender!).
A simple deactivation of the software is often not sufficient, as some of these programs continue to run in the background anyway:
C:\Program Files (x86)\GOG Galaxy\GalaxyClient.exe
C:\Program Files (x86)\GOG Galaxy\GalaxyClientService.exe
C:\ProgramData\GOG.com\Galaxy\redists\GalaxyCommunication.exe

A number of achievements for me aren't unlocking:
Treasure Hunter, Scrap Heaper, Growing Pains, Marathon, Arvantille's Angel...
23 others have unlocked, including Kickstopper, so I really have no idea what's going on.

I unlocked all achievement. I suggest loading old save file or start a new game and then try to unlock the achievement again, it is not an ideal solution but it might unlock the achievement.

I stopped playing and still waiting for a patch :(

If you started the game before the day one patch that might be it, if so only a new game might be the solution.

Then it's really weird, my internet is even kinda shit but I got all the achievements.
Maybe it's a firewall/antivirus/program files folder issue?
I keep all my games in a folder outside Program Files that is also whitelisted from Windows Defender.