crafting Flint tools crafting sometimes not work

[Laskuna]

Sometimes ( rare ) its imposible to craft (minigame with skulpting ) flint tools. Its imposible to remove voxels.
Happens to me, and my friend on multiplayer game. 

[Doot Doot Noot Noot]

you sure you're using a rock that is hard enough to remove the pieces? softer rocks wont work