I cannot find a way to remotely update iOS version for iPads by using Profile Manager as mobile device management (MDM) service. All devices are enrolled in Apple's DEP program.
I can choose Install Updates, select iOS 12 and press Install, but this won't install iOS 12. iPads will download iOS 12 but won't install. I need to open iPad cases and start using iPads to get the installation started. Doing this for hundreds of iPads is painful.