I'm trying to apply grass to a group, but when I got to render the grass doesn't show up, even though skatter is telling me that the group has the grass.
Are you using the latest version of Thea?
I have this version
You need to update Thea.
also it can clearly be seen that the grass is upside down because of face orientation which shows white on render but it`s actually making the grass grow on the other side of the face, be aware of that after the update!