Terraform editor:"0 Gene" instead of "0 general" & no option

I do not know why but in my current mission, when I am in the Terrain Terraform Editor, the first item which should be "0 General" with options about min height and increment, is instead a "0 Gene" with no options at all.

I only have this on my current mission. If I load another mission already done, I do not have this problem.

How do I fix this ?