The ruleset used within Upgrade Readiness - "Review applications with known issues" does not seem to be accurate. Within Upgrade Readiness I have the target version set to "Windows 10 Version 1709", but within the "Review applications with known issues" section it is reporting that valid/supported versions of DisplayLink (e.g. 8.3.x/8.4.x) are marked as issue: "Application is removed during upgrade". Similarly, with valid versions of Symantec Endpoint Protection (SEP) they are marked as issue: "Blocking upgrade, update application to newest version". In both cases upgrades from 1607/1703 to 1709 succeed without issue.
Hey Jeffrey, the "Review applications with known issues" section of UR is populated with data that comes directly from client machines. These are setup issues, but in many cases Microsoft has built-in remediations. For instance, the DisplayLink issue you mentioned ("App is removed during upgrade") will resolve itself during the upgrade process. The "Guidance" section of UR should indicate this (no action is required). That said, sometimes computers can report erroneous issues. If you'd like more info or would like us to drill into specific issues you're seeing your workspace, shoot us an email at firstname.lastname@example.org.