As I mentioned earlier, the disk temps are monitored by serial number and not DevX. You can check by looking in the /flash/config/smart-one.cfg file. See if the disk in question is in that file and has the settings you changed. If it does, then you may have found a bug. The problem is you are on 6.9 and you will be asked to upgrade to the latest version before any time will be spent on finding the problem. If I remember correctly, this was an issue in an earlier version and was fixed, but I don't remember the version.