Hello, there could be other explenation but try this one and see if it helps.
In new Portal go to Admin >> File Manager
create new folders within the portal named as follow:
images
docs
media
flash
than synchronise the files, and clear the cache.
Once completed you should be able to see the image,flash,document manager and media icons in the editor.
The reason for this is that when you created the subportal those folders were not created and the editor does not know where to find or save files.
Hope this helps