Exactly the same happen to me, all suggestions didn’t work.
There was a problem when trying to load the customizer.
Please open your browser debug tool , and report any error message (in red) printed in the javascript console in the Hueman theme forum .
Hi,
Wait for the customizer to be fully loaded before clicking on any option.
This will prevent error.
Please see my screen-cast.
http://screencast-o-matic.com/watch/cbfTVXXl8Z
I know it’s a very long wait, but if you click on any option before it fully loads, it will very likely to cause an error.
Thank you
Hello @wireinet, @sandrasamolik, thanks for reporting the problem. Yes this is currently an issue on some servers.
I am currently working on improving the performances on the initial loading phase.
This will be part of the next hueman addons release.
Before that, let us know if following Denzel’s recommendation helped.
Thank you
only one error in console:

ok thank you for this information.
A fix is on the way
Thank you!very need this!