I have a CHR which worked like it should for a months, but I think since the update of your website, the check for update is still shown from 7.20.4 → 7.20.6, but if you do “download & install”, something is downloaded and rebooted, but it’s staying at 7.20.4.
Now I looked at the website and did not find the ros-update package for the CHR.
I have no problem with the "Download&install" button on CHR to get 7.20.6 (I can switch between testing and stable and the right version, 7.20.6 or 7.21rc1, is being downloaded and installed correctly every time).
Please check if your license is still activated as a perpetual license and is not a trial 60-day license.