This happens when the ListGen Generator is used for the gen1 Generator of an Attribute within a Domain. If the setLoop Parameter has been set to "True" within the ListGen Generator, users will not be able to alter the Loop Count Value from the Scenario.
The Summary will show N <Domain Name>, and an Edit (Pencil) icon will not be present.
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If the setLoop Parameter is set to "False" for the Attribute gen1 Generator, the Loop Count Value can be modified from the Scenario.