Currently, devices are automatically removed from your Upgrade Readiness workspace if they have been inactive for a period of 90 days. In order to be consistent with other Windows Analytics solutions and to provide a more accurate representation of the active devices within your enterprise, we will be changing the Upgrade Readiness inactive device retention policy to 30 days on August 1st, 2017.
Most users will see little to no impact as a result of the change. As long as your computers are being actively used and are able to reach Microsoft's endpoints, they automatically send a heartbeat signal daily -- this is sufficient for us to consider the machine active. As always, we continue to recommend that you schedule the Upgrade Readiness deployment script to run on all of your computers once per month. This will ensure that the computers you manage send data to Microsoft successfully so that they remain in your Upgrade Readiness workspace.
To see if this change will affect your workspace, simply run this query (note that you should change the date to be 30 days prior to the current date when you run the query):
Type=UAComputer OR Type=UAUpgradedComputer LastScan<2017-06-18T00:00:00Z
Any computers returned by this query will be removed from your workspace once the inactive device retention policy change occurs. If you do not want some or all of these computers to be removed from your workspace, you simply need to run the deployment script on those machines before August 1st, 2017 to ensure that they are able to send data to Microsoft.