We have Ivanti 9.3 and use agents for our scanning. Recently, while moving up from 1703 to 1709 and 1803 on corporate PC's, about 1 in every 10 PC's would not show as being the upgraded version of the OS. After we upgrade the OS I always do a manual check in, upgrade binaries, upgrade patch and asset data and run patch and asset scans. For most machines this seem to cause Ivanti to display the correct OS version. But on the mentioned few, it can be days or weeks before the others show correct version. All use the same policy. I always verify OS version on the PC's prior to scanning using the winver command on the PC. Not a serious issue, just thought someone may have come across this and found an answer.
Thank you for posting your question and we apologize for the delay in responding.
One thing you will want to check is to make sure the agent actually rebooted so that the OS is scanned as the right version. The other thing you might want to check is the last scan date column in View > Machines as that will tell you whether or not the agent successfully scanned recently or not.