Some computers are not showing up in the CI's in a working Discovery setup.
Error in Discovery log files "Failed to read OS properties from AD!"
The root cause of this issue is missing properties in the AD information. See development explanation below of what ADScan looks for in the AD properties for OS.
If any of these three properties are missing in AD the error in the logs "Failed to read OS properties from AD!" will be seen.
The ADScan tries to find these three properties for the Operating System from AD.
And these properties are not always defined in the AD.
To confirm what is missing in the AD you can download the ADExplorer from https://technet.microsoft.com/en-us/sysinternals/bb963907.aspx?f=255&MSPPError=-2147217396.