Trying to unwrap sphere, seam in the middle

I have a sphere with the other side slightly edited, and a seam around the middle. WHY DOES IT DO THIS? I want 2 clean sides on the unwrap D:
When I make a fresh blender project with a similiar sphere from scratch it unwraps nicely

Make it a standard sphere, unwrap it, then modify the sphere while preserving the uv wrap intact.

If i make a new similiar, edited sphere on a different blender project why does it unwrap nicely and not this one?

edit:
Ok, I created a fresh, default sphere, make a seam go around the middle and unwrapped. The unwrap is still fucked up. Why cant I unwrap a sphere in this particular project file?

edit:
Creating the sphere as a new separate object instead of deleting the old sphere in edit mode and directly adding a new sphere to it worked. But I need to add it to the existing model because this sphere is a part of a bigger model.

Well, UV unwrapping tools in Blender have always been shitty, even in comparison with 3DS Max standart ones which came from 1990 without any changes to them. Try something except Blender maybe?

Can’t

[editline]20th October 2013[/editline]

I put the seam on a different axis and got this

which is still way too distorted for any texturing work

What im trying to get here is this, perfect unwrap without problems that dont make sense

[editline]20th October 2013[/editline]

Ok, managed to unwrap it through viewport which created perfect results.