This item has been identified as an outstanding known issue. A workaround is provided until the issue is officially fixed.
When selecting 'Manage Models' from Launchpad, the Anaplan UI is loaded, and nothing else. This looks like a blank model:
To work around this issue, simply navigate to 'Model Manager' again, from the empty UI/blank model.
If this workaround is not suitable in your use case, please contact Support at firstname.lastname@example.org.
Internal Reference: ECP-2848