Try this work around for now - something seems to be broken.
When you want to change you location back, slightly modify your registered phone number. So by default, Skype will show your previously registered phone number. Make a small change (e.g. change the last digit to another number). It should work then.
Your old registered phone number should still work, and the "new" one you just registered you can delete -> go to Registered phones on right hand side of the main Skype To Go tab and click on "Manage".
