Structure: List item IDs must be unique

Within a single list, there can be no duplicate IDs. The IDs are used to resolve which child to render as the next item. The Studio reports List items with same ID found (<ids>), naming up to five of the offending IDs. If a list item has no explicit ID, its ID is the camel-cased title — so titles that differ only in casing or punctuation collide.

If you are not manually assigning IDs, it probably means that the title of two or more of your list items are the same, since the ID is inferred from that if not specified.

When this is the case, you can solve it by calling id('someOtherId') on the list items that conflict.