I am having similar issues as mohaettayeb. I too have followed the documentation and have successfully installed theming. I was doing just fined, but once I added mutliple scss files, compiling the assets began failing
The latest error that I am getting is
ValueError: The file 'themes/code-ninja-edx/fonts/OpenSans/OpenSans-Light-webfont.woff2' could not be found with .
I've tried getting help through the Slack Channel for Open edX, but no solutions.
I've submitted a support ticket to Bitnami, but was told that since I don't have a Cloud account with them, they couldn't help and referred me to the community support docs.
I even spun up a new EC2 on AWS (m3.large .. so plenty of RAM) and all was going well, until I added multiple .scss files. Any help / direction would be appreciated.