It could be permission related, please verify the troubelshooting section in the above document. If you still have an issue I recommend you to open a TAC case for further troubleshooting as log files would be required.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...