In Evolve get the following message.
Object reference not set to an instance of an object.
In Log it shows
ERROR webDesignerLive.Areas.cwRestAPI.GlobalVariables 2018-01-22-10-28-43 – An Error occured while loading the engine for site <cmeip> : Casewise.GraphAPI.Exceptions.cwExceptionFatal: Required ObjectType ScriptName <FUNCTIONALLINE> does not exist in the model <CMEIP>
Evolve Site is down,
All Nodes are missing from Evolve site.
The object was deleted from the model, whiles still in use in Evolve.
Copy one test Object instance from a model back up and Import to the model with the problem. This will create a new object and its Object script name.
You can then open Evolve, remove the pages, republish. And only then delete the object in the design in Model Explorer.