After some changes in bitbake, it seems that Hob is not working ok. When you start Hob, you receive the following error:

Traceback (most recent call last):
  File "/home/cvoicu/dev/poky/bitbake/lib/bb/ui/crumbs/builder.py", line 853, in handler_command_succeeded_cb
    self.execute_after_sanity_check(self.switch_to_image_configuration_helper)
  File "/home/cvoicu/dev/poky/bitbake/lib/bb/ui/crumbs/builder.py", line 541, in execute_after_sanity_check
    func()
  File "/home/cvoicu/dev/poky/bitbake/lib/bb/ui/crumbs/builder.py", line 832, in switch_to_image_configuration_helper
    self.image_configuration_page.switch_machine_combo()
  File "/home/cvoicu/dev/poky/bitbake/lib/bb/ui/crumbs/imageconfigurationpage.py", line 341, in switch_machine_combo
    if model[0][0] != self.__dummy_machine__:
IndexError: could not find tree path

I have investigated it a little bit, but as RP said the errors in Hob are not well reported.