The scheduling option is available at the container level, not the device level. We may need to change this to allow scheduling in both places.
That forum post lists all the major new features added in 3.0.0 for both Essentials and X. This section lists the features that are only included in cnMaestro X. The forum formatting of section titles doesn’t make this very clear.
Edit: I should note the exact containers that support the configuration view are System, Network, Tower and AP Group.