The odd thing is that it was working a few days ago. Even uploaded a web scene to arcGIS online, straight from CityEngine without trouble. Not sure what changed, but I doubt it was a change in proxy or anything of the kind. And no issues accessing arcGIS online from arcGIS.
So it's a CityEngine issue.
I don't know if it's a coincidence but it seems to have changed after I exported for the first time a webscene to ZIP (right click .3ws file in catalog-> share as-> save package to file), rather than to arcGIS online.
In meantime, I've been exporting the scene as zip files and uploading them to arcGIS online in a browser. Which works. But still puzzled as to why it's disabled from within CE.
I am having the same problem... I just installed CE 2013 to see how the rpk export works, but i am not able to "Share" at all, the fields are gray. Just run the "Connection test", and passed all tests.
The first screenshot shows the result of right-clicking on the Scene-file in the navigator. It shows that Sharing is disabled (grey) [ATTACH=CONFIG]31063[/ATTACH]
The second screenshot is the result of "File-> Share As". With this option i am able to locate and select a exiting rpg-file, but the export result is zero. ( i tried it by creating a empty file with .rpg as extension) [ATTACH=CONFIG]31064[/ATTACH]
I hope you have enough information by now, if not: let me know