Not sure though But I assume this was removed due to the fact that if you would uninstall the application you and have articles as sortfield the site would crash and a fatal error would appea.
I know they tried to fix this fatal error site crash and i assume they did it this way.
But maybe Alexander will be able to say more about it.
So not sur eif that was fixed yet:
It does not seem like it according to the label.
I can sort by posts and i can uninstall the board app too so i dont think that thorey is correct.
I edited my first post.
It is not solved yet.
So I'm not what this causes this.
Maybe it should be moved to the error section then
Could be because Blog and Gallery are still 2.0 and not 2.1.