Unable to create a new property with type single page
We are unable to create a new property with the following error. Any suggestions /workaround? The issue seems to be that there is an existing page property with the same name in the inheritance hierarchy but the page definition class is different
From the screenshot, you are trying to edit a Page Property which is already created with a Page Definition with a new Page Definition.I don't think you can modify the PageDefinition of a Page property once created. Hence you are getting the error.
Once a property is created it doesnt allow to change the class of the property. This is the default expected behavior in the system. Also it doesnt allow to change the class in the lower class as well.
If your use case is to change the class of the Page Property at the lower class hierarchy then in the inheritance hierarchy Property make the Page Class as $CLASS and then system will allow you to give your correct class at the lower levels.