In previous Blender releases I’ve had no problems unwrapping all kinds of shapes, but in this new release which was supposed to enhance the unwrapping tools panel, it appears to be broken unfortunately.
For example a UV Sphere:
Preparation: (replace the two polar vertices with edge loops, and mark a seam stretching from north to south.)
In the past “Unwrap” would then give one a nice rectangular grid that one could fit over an entire image.
Now the Unwrap command produces unpredictable results. It’s also inconsistent, so make sure to hit ‘reset’ after each try.
I don’t know if I’m missing something or if a bug report has already been submitted.
Anyhow, please let me know if there is a solution to this.